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Imposing a pause between the eccentric and concentric phases increases the reliability of isoinertial strength assessments

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Abstract

Abstract This study analysed the effect of imposing a pause between the eccentric and concentric phases on the biological within-subject variation of velocity- and power-load isoinertial assessments. Seventeen resistance-trained athletes undertook a progressive loading test in the bench press (BP) and squat (SQ) exercises. Two trials at each load up to the one-repetition maximum (1RM) were performed using 2 techniques executed in random order: with (stop) and without (standard) a 2-s pause between the eccentric and concentric phases of each repetition. The stop technique resulted in a significantly lower coefficient of variation for the whole load-velocity relationship compared to the standard one, in both BP (2.9% vs. 4.1%; P = 0.02) and SQ (2.9% vs. 3.9%; P = 0.01). Test-retest intraclass correlation coefficients (ICCs) were r = 0.61-0.98 for the standard and r = 0.76-0.98 for the stop technique. Bland-Altman analysis showed that the error associated with the standard technique was 37.9% (BP) and 57.5% higher (SQ) than that associated with the stop technique. The biological within-subject variation is significantly reduced when a pause is imposed between the eccentric and concentric phases. Other relevant variables associated to the load-velocity and load-power relationships such as the contribution of the propulsive phase and the load that maximises power output remained basically unchanged.

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... Recently, isoinertial strength tests have been used to examine the kinetic and kinematic behavior by examining velocity-and power-load relationships during the concentric phase of a lift [7][8][9]. These studies have included a pause between the eccentric and concentric phases in order to minimize the contribution of the rebound effect and allow for more reproducible, consistent measurements during isoinertial strength tests [7][8][9]. ...
... Recently, isoinertial strength tests have been used to examine the kinetic and kinematic behavior by examining velocity-and power-load relationships during the concentric phase of a lift [7][8][9]. These studies have included a pause between the eccentric and concentric phases in order to minimize the contribution of the rebound effect and allow for more reproducible, consistent measurements during isoinertial strength tests [7][8][9]. However, it is well known that the stretch-shortening cycle (SSC) improves neuromuscular performance [10], influencing both the kinetics and kinematics of the movement in the subsequent concentric muscle action [11]. ...
... The authors found significant differences between light and high loads in the effect induced by the SSC [14]. However, Pallarés et al. (2014) determined that mechanical parameters linked to the load-power and load-velocity profiles (30-100% of 1RM) remained essentially unaffected by the SSC in BP and full squat exercises [7]. The authors concluded that the biological within-subject variation for the isoinertial strength assessment was decreased when a pause was established between the eccentric and concentric phases [7]. ...
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An isoinertial strength assessment was performed to examine the kinetic and kinematic behavior of the barbell during several muscle actions. Velocity–time characteristics, force–time relationship, one repetition maximum (1RM), power output, and acceleration were compared in eccentric–concentric (EC) versus concentric only (C) sequences of the bench press (BP) and military press (MP). In two separate sessions, 28 and 29 resistance-trained athletes executed EC or C sequences in random order of the BP and MP, respectively, in an incremental load test up to their 1RM. Higher values were recorded in BP-EC than in BP-C, MP-EC, or MP-C (p < 0.01) for peak acceleration, peak rate of force development, peak rate of velocity development, and power output. Significant differences were detected between exercises in terms of the portion of the concentric phase (%) at which peak acceleration was detected, or acceleration up until peak velocity was observed (p < 0.05). No differences were observed between exercises in the portion of the concentric phase where acceleration up to the braking phase took place. The eccentric muscle action prior to concentric movement was a key factor to enhance the kinematic and kinetic performance in BP exercise. No such effects of the countermovement were produced in MP.
... Mathematical models have been developed based on the load-velocity relationship to estimate the maximum force (expressed as 1RM) [6]. The general load-velocity relationship was introduced by Gonzalez-Badillo and Sanchez-Medina [7], who used a second-order polynomial regression equation to estimate %1RM during the bench press exercise based on velocity [6,[8][9][10][11][12][13][14]. The mathematical models use linear regressions between the load values (X) and AV (average velocity; Y). ...
... This was carried out by providing auditory and visual feedback in real time at a sampling rate of 1000 Hz. The transducer automatically determined the eccentric and concentric phases of each repetition, and the propulsive phase was defined as that portion of the concentric phase during which the measured acceleration (a) is greater than acceleration due to gravity (i.e., a ≥ −9.81 m·s −2 ) [8]. ...
... The weight was progressively increased by 3 kg for women and 5 kg for men. Three repetitions were performed for each weight until the MPV attained was lower than 0.50 m·s −1 [8]. From then on, progressive increases of 1 kg for women and 2 kg for men were implemented, and only two repetitions were performed. ...
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The purpose of this study was to determine the mean propulsive velocity (MVP) at various percentages of one repetition maximum (1RM) in the full squat and chest press exercises. A total of 96 young women and 256 young men (recreational athletes) performed an incremental test (50–60–70–80% 1RM) comprising the bench press and full squat exercises in two different sessions. The individual load and velocity ratios were established through the MPV. Data were analyzed using SPSS software version 25.0, with the significance level set at 5%. The following findings were revealed: highly linear load-velocity relationships in the group of women (r = 0.806 in the squat, and r = 0.872 in the bench press) and in the group of men (r = 0.832 and r = 0.880, respectively); significant differences (p < 0.001) in the MPV at 50–70–80% 1RM between the bench press and the full squat in men and at 70–80% 1RM in women; and a high variability in the MPV (11.49% to 22.63) in the bench press and full squat (11.58% to 25.15%) was observed in women and men (11.31% to 21.06%, and 9.26% to 24.2%) at the different percentages of 1RM evaluated. These results suggest that the load-velocity ratio in non-strength-trained subjects should be determined individually to more precisely establish the relative load to be used in a full squat and bench press training program.
... Additionally, lower-body strength gains following back-squat training have been shown to positively transfer to athletic performance during short duration high-intensity actions such as jumping and sprinting [17,18]. The back-squat exercise can be performed using the pause (i.e., a pause of 1-4 s is implemented between the lowering and lifting phases) or rebound techniques (i.e., the lifting phase is performed immediately after the lowering phase using the stretch-shortening cycle) [19,20]. Previous studies have reported acceptable levels of reliability for the measurements of MV, PV, MP, and PP (coefficient of variation [CV] ≤ 8.40%; intraclass correlation coefficient [ICC] ≥ 0.58) collected by the LPT GymAware PowerTool across a wide range of relative loads (20-90% of one-repetition maximum [1RM]) during the free-weight back-squat exercise performed with the rebound technique [10,12]. ...
... and PP (CV range = 3.60-7.40%). Moreover, the backsquat exercise has been shown to report more consistent velocity measurements using the pause technique compared to the rebound technique [19]. It should be also noted that machine-based exercises can provide more reliable measures of velocity than freeweight exercises [21], and, consequently, it is common that the testing procedures of mechanical performance against submaximal loads are performed in a Smith machine to reduce the noise of the test [11,[22][23][24]. ...
... Practitioners then need to decide whether the best (i.e., the highest) or the average value of these repetitions will be used for comparative analyses. Some studies have used the average score of all repetitions [10,11,14,15,22], other studies have used the best score [23,25], and others did not directly specify the repetition criteria used for data analysis [12,19]. Given the diversity of repetition criteria, previous research has explored whether the best or average scores are more appropriate as an indicator of physical performance [26][27][28][29]. ...
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This study aimed to compare the between-session reliability of different performance variables during 2 variants of the Smith machine back-squat exercise. Twenty-six male wrestlers performed 5 testing sessions (a 1-repetition maximum [1RM] session, and 4 experimental sessions [2 with the pause and 2 with the rebound technique]). Each experimental session consisted of per-forming 3 repetitions against 5 loads (45-55-65-75-85% of the 1RM). Mean velocity (MV), mean power (MP), peak velocity (PV), and peak power (PP) variables were recorded by a linear position transducer (GymAware PowerTool). The best and average scores of the 3 repetitions were con-sidered for statistical analyses. The coefficient of variation (CV) ranged from 3.89% (best PV score at 55%1RM using the pause technique) to 10.29% (average PP score at 85%1RM using the rebound technique). PP showed a lower reliability than MV, MP, and PV (CVratio≥1.26). The relia-bility was comparable between the exercise techniques (CVratio=1.08) and between the best and av-erage scores (CVratio=1.04). These results discourage the use of PP to assess back-squat performance at submaximal loads. The remaining variables (MV, MP, or PV), exercise techniques (pause or rebound), and repetition criteria (best score or average score) can be indistinctly used due to their acceptable and comparable reliability.
... In order to guarantee complete vertical linearity and minimize the velocity measurement variability in each repetition, a Smith machine (Technogym, Barcelona, Spain) was used, so that the participant paused briefly after the eccentric phase (between 1 and 1.5 seconds), supported by either the bar in a support, or the chest. This limited the countermovement, enabling greater control and reproducibility of the measurement in the concentric phase of movement [31]. For back squat execution, the subject was placed with the feet apart at shoulder height and the bar was placed on the shoulder blades with the hands gripping the bar, and then they flexed the knees at 120 ° followed by its extension to the original standing position. ...
... The recent Williams et al. study [15] was the first to measure the acute effects of BJ on power output and velocity during free-weight resistance exercise, specifically in bench press, in a population of resistance-trained men, finding improvements in mean velocity and power, in addition to a higher number of repetitions until failure in BJ compared to that in PLA, results that differ from those found in our study. The different results in velocity and power production with respect to Williams et al. [15] may be due to exercise equipment and the method used to measure the movement velocity, because our study was exclusively based on the analysis of the concentric movement phase of the exercise and was started from an isometric position, with a pause briefly after the eccentric phase (between 1 and 1.5 seconds), supported by either the bar or the chest, this reason could limit the differences in the mechanical variables associated with the load-velocity and the load-power profiles [31]. However, it would allow more reliable measurements in strength assessments based on movement velocity, in addition to the use of a Smith machine in order to limit the countermovement, enabling greater control and reproducibility of the measurement in the concentric phase of movement [31], unlike Williams et al. [15] who used a free-weight bench press in dynamic RT. ...
... The different results in velocity and power production with respect to Williams et al. [15] may be due to exercise equipment and the method used to measure the movement velocity, because our study was exclusively based on the analysis of the concentric movement phase of the exercise and was started from an isometric position, with a pause briefly after the eccentric phase (between 1 and 1.5 seconds), supported by either the bar or the chest, this reason could limit the differences in the mechanical variables associated with the load-velocity and the load-power profiles [31]. However, it would allow more reliable measurements in strength assessments based on movement velocity, in addition to the use of a Smith machine in order to limit the countermovement, enabling greater control and reproducibility of the measurement in the concentric phase of movement [31], unlike Williams et al. [15] who used a free-weight bench press in dynamic RT. In relation to this, other studies [38,39] demonstrated that BJ supplementation enhanced angular velocity and muscle power in knee extension evaluated in different populations, these results supporting the hypothesis that NO3 -influences the contractile properties of human muscle [38] according to previous studies in rats [17]. ...
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The ingestion of beetroot juice (BJ) has been associated with improvements in physical performance in endurance sports, however the literature on resistance training (RT) is scarce. The aim of this study was to investigate the acute effects of BJ compared to a placebo (PLA) on muscular endurance and movement concentric velocity during RT. Twelve healthy men performed an incremental RT test (back squat and bench press) with three sets, at 60%, 70%, and 80% of their repetition maximum (1-RM). Movement velocity variables, total number of repetitions performed until concentric failure, blood lactate, and ratings of perceived effort post-training were measured. A higher number of repetitions were recorded with BJ compared to those with PLA (13.8 ± 14.4; p < 0.01; effect size (ES) = 0.6). Differences were found at 60% 1-RM (9 ± 10; p < 0.05; ES = 0.61) and 70% 1-RM (3.1 ± 4.8; p < 0.05; ES = 0.49), however, no differences were found at 80% 1-RM (1.7 ± 1; p = 0.12; ES = 0.41). A greater number of repetitions was performed in back squat (13.4 ± 13; p < 0.01; ES = 0.77), but no differences were observed in bench press (0.4 ± 5.1; p = 0.785; ES = 0.03). No differences were found for the rest of the variables (p > 0.05). Acute supplementation of BJ improved muscular endurance performance in RT.
... This procedure represents the most precise methodology to prescribe the %1RM because it allows us to avoid the slight but meaningful betweensubject differences in the velocity attained to each %1RM (62). For Velocity-Based Resistance Training in Soccer VOLUME 00 | NUMBER 00 | FEBRUARY 2022 a Imposing a momentary pause for 2 seconds between the eccentric and concentric phases (31,34). Bench press and prone bench pull (49); full squat (paused) (29); full squat (nonpaused) (50); deadlift (33); shoulder press (21); pull-ups (51). ...
... Alternatively, different programming and dosing methodologies have emerged from the VBT, which goes beyond whether to reach or not the a Imposing a momentary pause for 2 seconds between the eccentric and concentric phases to increase reliability (31,34). SEE 5 standard error of estimation. ...
... In addition to reproducible and repeatable technologies, velocity-based assessments would benefit from (a) providing visual feedback to the athlete to maximize his or her performance (23) and (b) precise control of the execution technique. Regarding the second aspect, it has been proved that imposing a momentary pause (;2 seconds) between the eccentric and concentric phases (i.e., avoiding the stretchshortening cycle) produces more reliable velocity results during incremental loading tests (34) and allows players to precisely replicate the individual eccentric ROM in each repetition (28,29). In turn, the ROM has been shown to significantly influence the resulting velocity (the MPV increases as the ROM increases) (28,29). ...
... All exercises examined in the current study were executed by imposing a brief pause between the eccentric and concentric phases. In addition to precisely replicate the individual eccentric range of movement in each repetition (17,18) and increase the measure's reliability (21), results found by a recent velocity-based intervention suggested that imposing a brief pause between phases could maximize the neuromuscular adaptations (14). Thus, subjects were instructed to momentarily release the weight of the bar for ;1.5 seconds on 2 telescopic holders placed at the left and right sides of the Smith machine. ...
... Finally, we found a very strong relationship (R 2 $ 0.97) between the number of repetitions completed and the percentage of velocity Bench press VL (%) LOW (17) MED (18) HIGH (19) LOW (14) MED (15) HIGH (16) LOW (11) MED (12) HIGH (13) LOW (8) MED (10) HIGH (10) LOW (6) (19) MED (19) HIGH (19) LOW (15) MED (15) HIGH (15) LOW (11) MED (11) HIGH (13) LOW (9) MED (9) HIGH (9) LOW (6) MED (7) (14) MED (15) HIGH (16) LOW (11) MED (12) HIGH (14) LOW (9) MED (10) HIGH (11) LOW (7) MED (8) HIGH (9) LOW (5) (20) MED (20) HIGH (21) LOW (16) MED (16) HIGH (17) LOW (13) MED (13) HIGH (14) LOW (9) MED (10) HIGH (10) LOW (6) *VL 5 velocity loss; number in parentheses 5 nRM that could be completed at the specific %1RM. †Number as subscript: repetitions in reserve. ...
... Bench press VL (%) LOW (17) MED (18) HIGH (19) LOW (14) MED (15) HIGH (16) LOW (11) MED (12) HIGH (13) LOW (8) MED (10) HIGH (10) LOW (6) MED (7) HIGH ( (19) MED (19) HIGH (19) LOW (15) MED (15) HIGH (15) LOW (11) MED (11) HIGH (13) LOW (9) MED (9) HIGH (9) LOW (6) MED (7) HIGH (7 LOW (14) MED (15) HIGH (16) LOW (11) MED (12) HIGH (14) LOW (9) MED (10) HIGH (11) LOW (7) MED (8) HIGH (9) LOW (5) MED (6) HIGH (7) LOW (20) MED (20) HIGH (21) LOW (16) MED (16) HIGH (17) LOW (13) MED (13) HIGH (14) LOW (9) MED (10) HIGH (10) LOW (6) MED (6) HIGH (7) 10 ...
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Hernández-Belmonte, A, Courel-Ibáñez, J, Conesa-Ros, E, Martínez-Cava, A, and Pallarés, JG. Level of effort: A reliable and practical alternative to the velocity-based approach for monitoring resistance training. J Strength Cond Res XX(X): 000-000, 2021-This study analyzed the potential of the level of effort methodology as an accurate indicator of the programmed relative load (percentage of one-repetition maximum [%1RM]) and intraset volume of the set during resistance training in the bench press, full squat, shoulder press, and prone bench pull exercises, through 3 specific objectives: (a) to examine the intersubject and intrasubject variability in the number of repetitions to failure (nRM) against the actual %1RM lifted (adjusted by the individual velocity), (b) to investigate the relationship between the number of repetitions completed and velocity loss reached, and (c) to study the influence of the subject's strength level on the aforementioned parameters. After determining their individual load-velocity relationships, 30 subjects with low (n = 10), medium (n = 10), and high (n = 10) relative strength levels completed 2 rounds of nRM tests against their 65, 75, 85, and 95% 1RM in the 4 exercises. The velocity of all repetitions was monitored using a linear transducer. Intersubject and intrasubject variability analyses included the 95% confidence intervals (CIs) and the the standard error of measurement (SEM), respectively. Coefficient of determination (R2) was used as the indicator of relationship. nRM showed a limited intersubject (CI ≤ 4 repetitions) and a very low intrasubject (SEM ≤1.9 repetitions) variability for all the strength levels, %1RM, and exercises analyzed. A very close relationship (R2 ≥ 0.97) between the number of repetitions completed and the percentage of velocity loss reached (from 10 to 60%) was found. These findings strengthen the level of effort as a reliable, precise, and practical strategy for programming resistance training.
... These resistance exercises were chosen because of their relevance in resistance training, thus commonly used by conditioning specialists and coaches for sports training. Moreover, the intensity of 80% 1RM is widely used in traditional resistance training, and it is in the optimal range of relative intensities (30-80% 1RM) that have been suggested to improve long term muscular performance [27][28][29]. This resistance training was performed randomly after three different warm-ups: the progressive-intensity (WU) warm-up that included 2 sets of 6 repetitions, with 40% and 80% of the training load; the warm-up that included 1 set of 6 repetitions, with 80% of training load (WU80); the warm-up that included 1 set of 6 repetitions, with 40% of training load (WU40). ...
... They were instructed to lower the bar to the chest, just above the nipples, in a controlled manner, and, after approximately 1.0 s of pause, they started the concentric phase of the movement as fast as possible. The momentary pause at the chest between the eccentric and concentric actions was to minimize the contribution of the rebound effect and allow for more reproducible, consistent measurements [28]. The subjects were not allowed to bounce the bar of their chest or to raise their shoulders or trunk off the bench [21]. ...
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The current study aims to verify the effects of three specific warm-ups on squat and bench press resistance training. Forty resistance-trained males (19-30 years) performed 3 × 6 repetitions with 80% of maximal dynamic strength (designated as training load) after one of the following warm-ups (48 h between): (i) 2 × 6 repetitions with 40% and 80% of the training load (WU), (ii) 6 × 80% of training load (WU80), or (iii) 6 × 40% of the training load (WU40). Mean propulsive velocity (MPV), velocity loss (VL), peak velocity (PV), time to achieve PV, power, work, heart rates, and ratings of perceived exertion were analyzed. In squat exercises, higher MPV were found in WU80 compared with WU40 (2nd set: 0.69 ± 0.09 vs. 0.67 ± 0.06 m.s-1, p = 0.02, ES = 0.80; 3rd set: 0.68 ± 0.09 vs. 0.66 ± 0.07 m.s-1, p = 0.05, ES = 0.51). In bench press exercises, time to PV was lower in WU compared with WU40 (1st set: 574.77 ± 233.46 vs. 694.50 ± 211.71 m.s-1, p < 0.01, ES = 0.69; 2nd set: 533.19 ± 272.22 vs. 662.31 ± 257.51 m.s-1, p = 0.04, ES = 0.43) and total work was higher (4749.90 ± 1312.99 vs. 4631.80 ± 1355.01 j, p = 0.01, ES = 0.54). The results showed that force outputs were mainly optimized by WU80 in squat training and by WU in bench press training. Moreover, warming-up with few repetitions and low loads is not enough to optimize squat and bench press performances.
... The eccentric portion of the movement was executed in a continuous and controlled manner (2-3 s) with a momentary pause (~1.5 s) between the eccentric and concentric phases to minimize the contribution of the rebound effect and provide more reliable data for both exercises [24]. The duration of the eccentric and isometric phases was paced by one of the investigators. ...
... These data strongly support previous studies showing that mechanical power output is quite similar across a range of light-moderate loads in other resistance exercises such as the bench press (20-60% 1RM) [37], bench pull (20-70% 1RM) (37), traditional deadlift (40-80% 1RM) [17], and half-BSQ (25-85% 1RM) [10]. These findings raise some questions about how much attention has been given to determining a single "optimal load" [24,37,38]. This is supported by previous studies showing improvements in strength-power ability using a wide range of moderate (i.e. ...
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The aim of this study was to analyse the load-velocity and load-power relationships in the free-weight back-squat (BSQ) and hexagonal bar deadlift (HBD) exercises. Twenty-five (n = 25) resistance-trained men (age = 23.7 ± 2.8 years) performed a progressive load test at maximal intended velocity to determine their BSQ and HBD one-repetition maximum (1RM). Mean propulsive velocity (MPV) during the concentric phase of the lift was recorded through a linear encoder. Load-velocity and load-power relationships were analysed by fitting linear regression and the second-order polynomial, respectively, to the data. Maximum strength (1RM), MPV (30–80% 1RM), and power output (30–90% 1RM) were higher for HBD compared to BSQ exercise (p < 0.05). A very strong relationship between MPV and relative intensity was found for both BSQ (R2 = 0.963) and HBD (R2 = 0.967) exercises. The load that maximizes power output (Pmax) was 64.6 ± 2.9% (BSQ) and 59.6 ± 1.1% (HBD) 1RM. There was a range of loads at which power output was not different than Pmax (BSQ: 40–80% 1RM; HBD: 50–70% 1RM). In conclusion, the load-velocity and load-power relationships might assist strength and conditioning coaches to monitor and prescribe exercise intensity in the BSQ and HBD exercises using the velocity-based training approach.
... Mean velocity (i.e., the average velocity across the concentric phase) of all the repetitions performed at each relative load was recorded by a linear position transducer. Thereafter, four velocity-based methods were used to predict 1RM; the data of seven loads (20,30,40,50, 60, 70, and 80% 1RM; i.e., multiple-load method), two distant loads (20 and 80% 1RM; i.e., distant two-point method), two light loads (20 and 40% 1RM; i.e., low method), and two heavy loads (60 and 80% 1RM; i.e., high-load method) were used to model the individual load-velocity relationships by linear regression. The 1RM was estimated from the load-velocity relationship as the load associated with reference MVT values of 0.17 m·s −1 for bench press [10,15], 0.37 m·s −1 for back squat [20], and 0.40 m·s −1 for bent-over-row [21]. ...
... Thereafter, four velocity-based methods were used to predict 1RM; the data of seven loads (20,30,40,50, 60, 70, and 80% 1RM; i.e., multiple-load method), two distant loads (20 and 80% 1RM; i.e., distant two-point method), two light loads (20 and 40% 1RM; i.e., low method), and two heavy loads (60 and 80% 1RM; i.e., high-load method) were used to model the individual load-velocity relationships by linear regression. The 1RM was estimated from the load-velocity relationship as the load associated with reference MVT values of 0.17 m·s −1 for bench press [10,15], 0.37 m·s −1 for back squat [20], and 0.40 m·s −1 for bent-over-row [21]. ...
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Background: This study determined the accuracy of different velocity-based methods when predicting one-repetition maximum (1RM) in young and middle-aged resistance-trained males. Methods: Two days after maximal strength testing, 20 young (age 21.0 ± 1.6 years) and 20 middle-aged (age 42.6 ± 6.7 years) resistance-trained males completed three repetitions of bench press, back squat, and bent-over-row at loads corresponding to 20-80% 1RM. Using reference minimum velocity threshold (MVT) values, the 1RM was estimated from the load-velocity relationships through multiple (20, 30, 40, 50, 60, 70, and 80% 1RM), two-point (20 and 80% 1RM), high-load (60 and 80% 1RM) and low-load (20 and 40% 1RM) methods for each group. Results: Despite most prediction methods demonstrating acceptable correlations (r = 0.55 to 0.96), the absolute errors for young and middle-aged groups were generally moderate to high for bench press (absolute errors = 8.2 to 14.2% and 8.6 to 20.4%, respectively) and bent-over-row (absolute error = 14.9 to 19.9% and 8.6 to 18.2%, respectively). For squats, the absolute errors were lower in the young group (5.7 to 13.4%) than the middle-aged group (13.2 to 17.0%) but still unacceptable. Conclusion: These findings suggest that reference MVTs cannot accurately predict the 1RM in these populations. Therefore, practitioners need to directly assess 1RM.
... 2,7,8 Despite the fact that this pause would increase the measure's reliability (lower within-subject variation), 9 different investigations have found that a large stop between the lengthening (eccentric) and shortening (concentric) phases decreases substantially the subsequent concentric performance. [9][10][11] This fact could be explained by the dissipation of the elastic energy stored in the muscle series' elastic components and the reduction of the reflexively induced neural input and potentiation of the contractile machinery. [11][12][13][14] Nevertheless, although there is a clear consensus about the superior acute effects (ie, short-term) of rebound SQ executions (REBOUND) compared with pause SQ contractions (PAUSE), no study has yet investigated the differences in longitudinal adaptations of both SQ executions through a resistance training intervention. ...
... (Table 2, Figure 2). Although previous investigations have compared the acute effects of PAUSE and REBOUND techniques, 9,10 to the best of authors' knowledge, this is the first investigation comparing the longitudinal effects of both techniques in the SQ exercise. Results found by the current research could suggest differences between short-and long-term effects of these SQ variants. ...
Article
Purpose: A variation of the traditional squat (SQ) rebound technique (REBOUND) including a momentary pause ∼2 seconds (PAUSE) between eccentric and concentric phases has been proposed. Although there is a consensus about the lower acute effects on performance of this PAUSE variant compared with traditional REBOUND technique, no information exists about the differences in longitudinal adaptations of these SQ executions. Methods: A total of 26 men were randomly assigned into the PAUSE (n = 13) or REBOUND (n = 13) groups and completed a 10-week velocity-based training using the SQ exercise, only differing in the technique. Neuromuscular adaptations were assessed by the changes in the 1-repetition maximum strength and mean propulsive velocity achieved against the absolute loads (in kilograms) common to pretest and posttest. Functional performance was evaluated by the following tests: countermovement jump, Wingate, and sprint time at 0 to 10, 10 to 20, and 0 to 20 m. Results: Whereas both groups showed significant increases in most of the neuromuscular tests (P < .05), the PAUSE (effect size [ES] = 0.76-1.12) presented greater enhancements than REBOUND (ES = 0.45-0.92). Although not significant, improvements in Wingate and sprint time at 0 to 10 and 0 to 20 m were higher for PAUSE (ES = 0.31-0.46) compared with REBOUND (ES = 0.10-0.29). Conversely, changes on countermovement jump and sprint time at 10 to 20 m were superior for REBOUND (ES = 0.17-0.88) than for PAUSE (ES = 0.09-0.75). Conclusion: Imposing a pause between eccentric and concentric phases in the SQ exercise could be an interesting strategy to increase neuromuscular and functional adaptations in sport actions that mainly depend on concentric contractions. Moreover, sport abilities highly dependent on the stretch-shortening cycle could benefit from the REBOUND or a combination of the 2 techniques.
... Because the load-velocity relationship varies among exercises, the knowledge of particular equations is indispensable to effectively implement the VBT method. Whereas the load-velocity relationship of exercises such as the bench press [5,[10][11][12], squat [4,6,12] A comprehensive analysis of the velocity-based method in the shoulder press exercise: stability of the load-velocity relationship and sticking region parameters Subjects Forty-eight men (age 22.1 ± 3.5 years, body mass 76.3 ± 8.8 kg, height 175.8 ± 5.9 cm) volunteered to take part in this study. Inclusion criteria were: i) having a relative strength ratio (RSR = 1RM weight lifted/body mass) higher than 0.60 in the SP exercise and ii) no health problems, physical limitations or musculoskeletal injuries that could affect the technical executions. ...
... Because the load-velocity relationship varies among exercises, the knowledge of particular equations is indispensable to effectively implement the VBT method. Whereas the load-velocity relationship of exercises such as the bench press [5,[10][11][12], squat [4,6,12] A comprehensive analysis of the velocity-based method in the shoulder press exercise: stability of the load-velocity relationship and sticking region parameters Subjects Forty-eight men (age 22.1 ± 3.5 years, body mass 76.3 ± 8.8 kg, height 175.8 ± 5.9 cm) volunteered to take part in this study. Inclusion criteria were: i) having a relative strength ratio (RSR = 1RM weight lifted/body mass) higher than 0.60 in the SP exercise and ii) no health problems, physical limitations or musculoskeletal injuries that could affect the technical executions. ...
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The purpose of this study was threefold: i) to analyse the load-velocity relationship of the shoulder press (SP) exercise, ii) to investigate the stability (intra-individual variability) of this load-velocity relationship for athletes with different relative strength levels, and after a 10-week velocity-based resistance training (VBT), and iii) to describe the velocity-time pattern of the SP: first peak velocity [Vmax1], minimum velocity [Vmin], and second peak velocity [Vmax2]. This study involves a cross-sectional (T1, n = 48 subjects with low, medium and high strength levels) and longitudinal (T2, n = 24 subjects randomly selected from T1 sample) design. In T1, subjects completed a progressive loading test up to the 1RM in the SP exercise. The barbell mean, peak and mean propulsive velocities (MV, PV and MPV) were monitored. In T2, subjects repeated the loading test after 10 weeks of VBT. There were very close relationships between the %1RM and velocity attained in the three velocity outcomes (T1, R2 : MV = 0.970; MPV = 0.969; PV = 0.954), being even stronger at the individual level (T1, R2 = 0.973–0.997). The MPV attained at the 1RM (~0.19 m·s-1) was consistent among different strength levels. Despite the fact that 1RM increased ~17.5% after the VBT programme, average MPV along the load-velocity relationship remained unaltered between T1 and T2 (0.69 ± 0.06 vs. 0.70 ± 0.06 m·s-1). Lastly, the three key parameters of the velocity-time curve were detected from loads > 74.9% 1RM at 14.3% (Vmax1), 46.1% (Vmin), and 88.7% (Vmax2) of the concentric phase. These results may serve as a practical guideline to effectively implement the velocity-based method in the SP exercise.
... The first load for the half-squat exercise was set at 20 kg with increases of 10 kg for each consecutive set, while for the LSJ, the first load was set at 40% of body mass with increases of 10% of body mass (Conceicao et al., 2016;Loturco et al., 2015). In order to minimize the stretchshortening cycle while allowing for consistent and reliable measurements (Pallares et al., 2014), the eccentric phase was performed in a controlled manner (0.3-0.5 m·s −1 ) with a momentary stop (~1 s) before the execution of the concentric phase. Also, a goniometer was used to ensure a 90° angle at the knee during the assessments. ...
Article
We aimed to develop models to explain performance and pacing during a 10-km running trial. Well-trained runners (n = 27, VO2max = 62.3 ± 4.5 mL·kg⁻¹·min⁻¹) divided into High (HPG, T10km = 33.9 ± 1.2 min, n = 9) and Low (LPG, T10km = 37.9 ± 1.2 min, n = 18) performers completed, in different days, the half squat and loaded squat jump (LSJ) exercises (1st day), an incremental test and a submaximal running bout to induce jump potentiation (2nd day), and a 10-km time trial (3rd day). Pacing was significantly different between performance groups (p < 0.05). The inclusion of mechanical and metabolic variables increased the explained variance in performance (LPG, r²adj = 0.87, p < 0.001; HPG, r²adj = 0.99 p < 0.01). Analysis between potentiation and non-potentiation groups revealed significant differences for the speed in the last 400 m (p = 0.02), and in the final RPE (p = 0.03). Performance and pacing can be explained by combining metabolic and mechanical variables and should be controlled by performance level. The relationship between jump potentiation and speed during the last 400 m may suggest that post-activation performance enhancement could be involved in pacing regulation.
... m·s 21 ) and to maintain a static position for ;1 second at the end of this phase (i.e., ;1 cm above each subject's chest at the bar holders), and thereafter, they performed a purely concentric push at maximal intended velocity. This momentary pause between phases was imposed to minimize the contribution of the rebound effect and allow for more reproducible measurements (31). Each subject was carefully instructed to always perform the concentric phase of each repetition in an explosive manner but throwing the bar at the end of the concentric phase was Performance and Neuromuscular Activity During Cluster Sets (2020) 00:00 not allowed. ...
Article
The aim of this study was to compare the effects of different cluster set (CS) configurations on mechanical performance and electromyography (EMG) activity during the bench press (BP) exercise. Fourteen strength-trained men (age 23.062.4 years; height 1.7660.08 m; body mass 78.3612.2 kg) performed 3 different protocols in the BP exercise consisting of 3 sets of 12 repetitions at 60% of 1 repetition maximum with interset rests of 2 minutes, differing in the set configuration: (a) traditional sets (TRDs), (b) cluster sets of 4 repetitions (CS4), and (c) cluster sets of 2 repetitions (CS2). Intraset rests of 30 seconds were interposed for CS protocols. The mean propulsive values of force, velocity, and power output were measured for every repetition by synchronizing a linear velocity transducer with a force platform. The root mean square (RMS) and median frequency (MDF) for pectoralis major (PM) and triceps brachii (TB) muscles were also recorded for every repetition. Force, velocity, and power values progressively increased as the number of intraset rests increased (TRD,CS4,CS2). The CS2 protocol exhibited lower RMS-PM than CS4 and TRD for almost all sets. In addition, TRDs showed significantly lower MDF-TB than CS2 for all sets and lower MDF-TB than CS4 during the third set. In conclusion, more frequent intraset rests were beneficial for maintaining mechanical performance, which may be mediated, from a neuromuscular perspective, by lesser increases in EMG amplitude and attenuated reductions in EMG frequency.
... This may be due to natural movements of the shoulder in the population tested, where the ER phase is predominantly eccentric, while the IR contraction is substantially concentric (Wagner et al., 2012). However, limits of agreement are wider in an eccentric phase like results obtained in (Pallarés et al., 2014), testing a stop between phases for a better adaptation of the subjects (Figs. 4 and 5). Clinicians and trainers should take these results into account to individualize the evaluation protocols according to the type of population and problem, whether they are overhead athletes or populations at risk of chronic pain in the shoulder. ...
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Background: The evaluation of the force in internal rotation (IR) and external rotation (ER) of the shoulder is commonly used to diagnose possible pathologies or disorders in the glenohumeral joint and to assess patient's status and progression over time. Currently, there is new technology of multiple joint isokinetic dynamometry that allows to evaluate the strength in the human being. The main purpose of this study was to determine the absolute and relative reliability of concentric and eccentric internal and external shoulder rotators with a functional electromechanical dynamometer (FEMD). Methods: Thirty-two male individuals (21.46 ± 2.1 years) were examined of concentric and eccentric strength of shoulder internal and external rotation with a FEMD at velocities of 0.3 m s-1 and 0.6 m s-1. Relative reliability was determined by intraclass correlation coefficients (ICC). Absolute reliability was quantified by standard error of measurement (SEM) and coefficient of variation (CV). Systematic differences across velocities testing circumstances, were analyzed with dependent t tests or repeated-measures analysis of variance in case of 2 or more than 2 conditions, respectively. Results: Reliability was high to excellent for IR and ER on concentric and eccentric strength measurements, regardless of velocity used (ICC: 0.81-0.98, CV: 5.12-8.27% SEM: 4.06-15.04N). Concentric outcomes were more reliable than eccentric due to the possible familiarization of the population with the different stimuli. Conclusion: All procedures examined showed high to excellent reliability for clinical use. However, a velocity of 0.60 m s-1 should be recommended for asymptomatic male patients because it demands less time for evaluation and patients find it more comfortable.
... The protocol of the study was authorised by the ethics committee of the university, following the principles of the Declaration of Helsinki [16]. execution of the BP exercise was as follows: in the supine position on the bench, with the hips and knees flexed and the feet on the bench; the arms slightly more open than shoulder width; the bar was brought down gently and slowly to the chest, right above the intermamillary line; the bar was held on the chest for approximately 2 s, in order to remove the bouncing effect and improve the reliability of the measurements [17]. The order of executing the concentric phase was verbally given by one of the researchers, counting the 2 s stop between the eccentric phase and the concentric phase. ...
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Background: The aim of this study was to verify the reproducibility of a resistance training protocol in the bench press (BP) exercise, based on traditional recommendations, analysing the effect of the muscle fatigue of each set and of the whole exercise protocol. Methods: In this cross-sectional study, thirty male physical education students were divided into three groups according to their relative strength ratio (RSR), and they performed a 1RM BP test (T1). In the second session (T2), which was one week after T1, the participants performed a BP exercise protocol of three sets with the maximum number of repetitions (MNR) possible to muscle failure, using a relative load corresponding to 70% 1RM determined through the mean propulsive velocity (MPV) obtained from the individual load-velocity relationship, with 2 min rests between sets. Two weeks later, a third session (T3) identical to the second session (T2) was performed. The MPV of each repetition of each set and the blood lactate level after each set were calculated, and mechanical fatigue was quantified through the velocity loss percentage of the set (% loss MPV) and in a pre-post exercise test with an individual load that could be lifted at ~1 m·s-1 of MPV. Results: The number of repetitions performed in each set was significantly different (MNR for the total group of participants: set 1 = 12.50 ± 2.19 repetitions, set 2 = 6.06 ± 1.98 repetitions and set 3 = 4.20 ± 1.99 repetitions), showing high variation coefficients in each of the sets and between groups according to RSR. There were significant differences also in MPVrep Best (set 1 = 0.62 ± 0.10 m·s-1, set 2 = 0.42 ± 0.07 m·s-1, set 3 = 0.36 ± 0.10 m·s-1), which significantly reduced the % loss MPV of all sets (set 1 = 77.4%, set 2 = 64%, set 3 = 54.2%). The lactate levels increased significantly (p < 0.05) (set 1 = 4.9 mmo·L-1, set 2 = 6 mmo·L-1, set 3 = 6.5 mmo·L-1), and MPV loss at 1 m·s-1 after performing the three sets was 36% in T2 and 34% in T3, with acceptable intrasubject variability (MPV at 1 m·s-1 pre-exercise: SEM ≤ 0.09 m·s-1, CV = 9.8%; MPV at 1 m·s-1 post-exercise: SEM ≤ 0.07 m·s-1, CV = 11.7%). Conclusions: These exercise propositions are difficult to reproduce and apply. Moreover, the number of repetitions performed in each set was significantly different, which makes it difficult to define and control the intensity of the exercise. Lastly, the fatigue generated in each set could have an individual response depending on the capacity of each subject to recover from the preceding maximum effort.
... The test was performed on a Smith machine device (Hammer-Strength Equipment, IL). Athletes were required to execute the eccentric phase in a controlled manner and maintain a static position for ;1 second at the end of this phase, with the bar slightly touching the chest, to reduce the contribution of the rebound effect and provide more consistent measures (21). Next, they were required to perform the concentric action with maximal intent. ...
Article
The purpose of this study was to determine the relative load (% of one-repetition maximum [1RM]) at which the concentric action becomes entirely propulsive in the bench-press (BP) exercise and verify whether this relative load varies between athletes with different strength levels. Twenty-eight professional athletes (Olympic boxers, professional mixed martial arts fighters, and elite rugby players) performed a progressive loading test up to their 1RM in the BP exercise (BP-1RM). Athletes were ordered according to their relative strength values and equally divided into two different groups: “low” (≤1.34) and “high” (≥1.38) strength levels. An independent t-test was used to compare the variables between groups. Significance level was set at P< 0.05. No significant differences were observed between the groups for the mean propulsive velocity attained at 1RM and for the maximum load that required braking action during the execution of the traditional BP exercise (ES = 0.27 and 0.15, respectively; P> 0.05). Our results revealed that at 80% 1RM the concentric action can already be considered as 100% propulsive in the BP exercise. Importantly, this occurrence was independent of strength level. Therefore, this relative strength measure (i.e., 80% BP-1RM) may be used as a reference for the 1RM in the BP throw.
... e. bar resting on the chest) before performing the concentric phase at maximal intended velocity upon hearing the command. This pause was interposed between the eccentric and concentric phases to minimize the contribution of the rebound effect and allow for more reproducible measurements [30]. Throwing the bar at the end of the concentric phase was not allowed. ...
Article
This study aimed to examine the validity of using bar velocity to estimate relative load in squat and bench-press exercises for both young men and women. Twenty-five men and 25 women performed a progressive loading test up to 1-RM in the squat and bench-press exercises, which were repeated after 2-weeks. Relationships between mean propulsive velocity and%1-RM were analysed. A second-order polynomial equation for predicting the corresponding velocity of each percentage of 1-RM was developed for men (validation). This equation was then applied in women (cross-validation). Moreover, a specific equation for women was developed (validation) and was also applied in a sub-sample of women (cross-validation). Close relationships (R2: 0.91–0.95) between bar velocity and relative load were observed in both sexes for squat and bench press. Men’s equation applied to women showed a high level of agreement, although lower bias and higher level of agreement was observed when a sex-specific equation was applied in women, both validation and cross-validation samples. In conclusion, lifting velocity can be used to accurately prescribe the relative load regardless of sex in both upper-body and lower-body exercises, although when estimating load from velocity measures it will be necessary to use the sex-specific equation for each exercise.
... During each repetition, the subjects were required to perform the eccentric phase in a controlled manner and to maintain a static position for ~1 second at the end of this phase (ie bar resting on the chest) to minimize the contribution of the rebound effect and allow for more reproducible measurements. 26 Then, the bar was lifted at maximal intended velocity upon hearing the command. Throwing the bar at the end of the concentric phase was not allowed. ...
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Objective This study aimed to compare the effects of four velocity‐based training (VBT) programs in bench‐press (BP) between a wide range of velocity loss (VL) thresholds – 0% (VL0), 15% (VL15), 25% (VL25) and 50% (VL50) – on strength gains, neuromuscular adaptations and muscle hypertrophy. Methods Sixty‐four resistance‐trained young men were randomly assigned into four groups (VL0, VL15, VL25, and VL50) that differed in the VL allowed in each set. Subjects followed a VBT program for 8‐weeks using the BP exercise. Before and after the VBT program the following tests were performed: 1) cross‐sectional area (CSA) measurements of pectoralis major (PM) muscle; 2) maximal isometric test; 3) progressive loading test; and 4) fatigue test. Results Significant group x time interactions were observed for CSA (P<0.01) and peak root mean square in PM (peak RMS‐PM, P<0.05). VL50 showed significantly greater gains in CSA than VL0 (P<0.05). Only the VL15 group showed significant increases in peak RMS‐PM (P<0.01). Moreover, only VL0 showed significant gains in the early rate of force development (RFD, P=0.05), while VL25 and VL50 improved in the late RFD (P≤0.01–0.05). No significant group × time interactions were found for any of the dynamic strength variables analyzed, although all groups showed significant improvements in all these parameters. Conclusion Higher VL thresholds allowed for a greater volume load which maximized muscle hypertrophy, whereas lower VL thresholds evoked positive neuromuscular‐related adaptations. No significant differences were found between groups for strength gains, despite the wide differences in the total volume accumulated by each group.
... Each participant lowered the bar in a continuous motion until the grip attained chest height. A brief pause (~1.5 s) was imposed bet ween the eccentric and concentric actions to minimize any rebound effect and allow for more reproducible measurements [20]. On hear ing a signal from the evaluator, the participants performed the concentric phase at maximal volitional velocity. ...
Article
This study aimed to analyze the effects of three different velocity loss thresholds (10%: VL10, 30%: VL30 and 50%: VL50) on maximal strength and velocity at different intensities during bench press using a weight stack machine (WSM-BP). Forty-five men were randomly assigned to three groups: VL10 (n=15), VL30 (n=15) and VL50 (n=15), which followed a 5-week (15 sessions) velocity-based WSM-BP program. Assessments performed Pre- and Post-training included: a) estimated one-repetition maximum (1RM) in WSM-BP; b) average velocity attained against all absolute loads common to Pre- and Post-training tests in WSM-BP; c) average velocity attained against all absolute loads that were lifted equal to or faster than 0.8 m·s−1 at Pre-training (light loads); and d) average velocity attained against all absolute loads that were lifted slower than 0.8 m·s−1 at Pre-training (heavy loads). All groups showed significant improvements in 1RM, velocity against all loads, and velocity against heavy loads (P<0.001–0.01). However, only the VL10 group showed significant enhancements in velocity against light loads (P=0.05). Therefore, the VL10 group showed a higher training efficiency compared to VL30 and VL50 interventions, since it obtained similar benefits by performing fewer repetitions.
... The bar was required to remain in contact with the back and shoulders at all times [42]. From this position, they were required to descend until making contact with the bench and then perform the concentric phase of the movement in an explosive manner [43,44]. The height of the bench was individually selected and allowed each participant to descend with the hips below the knee line according to the rules of the International Powerlifting Federation (IPF). ...
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The aim of the present study was to evaluate the effects of external compression with blood flow restriction on power output and bar velocity changes during the back-squat exercise (SQ). The study included 10 judo athletes (age = 28.4 ± 5.8 years; body mass = 81.3 ± 13.1 kg; SQ one-repetition maximum (1-RM) 152 ± 34 kg; training experience 10.7 ± 2.3 years). Methods: The experiment was performed following a randomized crossover design, where each participant performed three different exercise protocols: (1) control, without external compression (CONT); (2) intermittent external compression with pressure of 100% arterial occlusion pressure (AOP) (EC-100); and (3) intermittent external compression with pressure of 150% AOP (EC-150). To assess the differences between conditions, the participants performed 3 sets of 3 repetitions of the SQ at 70% 1-RM. The differences in peak power output (PP), mean power output (MP), peak bar velocity (PV), and mean bar velocity (MV) between the three conditions were examined using repeated measures two-way ANOVA. Results: The post hoc analysis for the main effect of conditions showed a significant increase in PP (p = 0.03), PV (p = 0.02), MP (p = 0.04), and MV (p = 0.03), for the EC-150, compared to the CONT. Furthermore, a statistically significant increase in PP (p = 0.04), PV (p = 0.03), MP (p = 0.02), and MV (p = 0.01) were observed for the EC-150 compared to EC-100. There were no significant changes in PP, PV, MP, and MV, between EC-100 and CONT conditions. Conclusion: The results indicate that the use of extremely high-pressure external compression (150% AOP) during high-loaded (70% 1-RM) lower limb resistance exercise elicits an acute increase in power output and bar velocity.
... These results suggest that the testing procedure needed to estimate the DLn 1RM in our sample of subjects may have been simplified by using a general V1RM of 0.37 m·s 21 , if sport professionals are willing to accept 6.6 kg of absolute error rates. However, more studies are needed to elucidate whether the general V1RM should be population-specific (i.e., varying between athletes from different sports) because highly resistance-trained athletes may show a lower V1RM than less-trained athletes (17,26). Future studies should be conducted to determine the general V1RM that provides the most accurate estimation of the 1RM in different exercises and to elucidate whether this general V1RM should be modified based on certain subject's characteristics such as training background, strength levels, or anthropometric characteristics. ...
Article
Jukic, I, García-Ramos, A, Malecek, J, Omcirk, D, and Tufano, JJ. Validity of load-velocity relationship to predict 1 repetition maximum during deadlifts performed with and without lifting straps: the accuracy of six prediction models. J Strength Cond Res XX(X): 000-000, 2020-This study aimed to compare the accuracy of six 1 repetition maximum (1RM) prediction models during deadlifts performed with (DLw) and without (DLn) lifting straps. In a counterbalanced order, 18 resistance-trained men performed 2 sessions that consisted of an incremental loading test (20-40-60-80-90% of 1RM) followed by 1RM attempts during the DLn (1RM = 162.0 ± 26.9 kg) and DLw (1RM = 179.0 ± 29.9 kg). Predicted 1RMs were calculated by entering both group and individualized mean concentric velocity of the 1RM (V1RM) into an individualized linear and polynomial regression equations, which were derived from the load-velocity relationship of 5 ([20-40-60-80-90% of 1RM], i.e., multiple-point method) or 2 ([40 and 90% of 1RM] i.e., 2-point method) incremental warm-up sets. The predicted 1RMs were deemed highly valid if the following criteria were met: trivial to small effect size, practically perfect r, and low absolute errors (<5 kg). The main findings revealed that although prediction models were more accurate during the DLn than DLw, none of the models provided an accurate estimation of the 1RM during both DLn (r = 0.92-0.98; absolute errors: 6.6-8.1 kg) and DLw (r = 0.80-0.93; absolute errors: 12.4-16.3 kg) according to our criteria. Therefore, these results suggest that the 1RM for both DLn and DLw should not be estimated through the recording of movement velocity if sport professionals are not willing to accept more than 5 kg of absolute errors.
... Back Squat Exercise. The exercise performed in the study was the back squat up to 90°of flexion with a complete stop to avoid the myotatic reflex (28). In strength training, the squat exercise has traditionally been considered one of the main performance indicators and, therefore, is included in the training plan of different sports (47). ...
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Gómez-Carmona, CD, Bastida-Castillo, A, Rojas-Valverde, D, de la Cruz Sánchez, E, García-Rubio, J, Ibáñez, SJ, and Pino-Ortega, J. Lower-limb dynamics of muscle oxygen saturation during the back-squat exercise: effects of training load and effort level. J Strength Cond Res XX(X): 000-000, 2019-The aim of this study was to analyze the effect of strength training on lower limb muscle oxygenation. The sample consisted of 12 male subjects (22.4 ± 1.73 years; 1.81 ± 0.08 cm height and 77.76 ± 8.77 kg body mass). Six different strength training stimuli were analyzed, based on the training variables: load (60-75% 1 repetition maximum [1RM]) and level of effort (LE) (E1: 4 × 8 [20RM], E2: 4 × 12 [20RM], E3: 4 × 16 [20RM], E4: 4 × 4 [10RM], E5: 4 × 6 [10RM], and E6: 4 × 8 [10RM]) in the squat exercise up to 90° with a 2-second stop between repetitions to avoid the myotatic reflex. Oxygen saturation at the beginning of the series (SmO2start), oxygen saturation at the end of the series (SmO2stop), percentage of oxygen saturation loss (▽%SmO2), and reoxygenation time (SmO2recT) were assessed using a near-infrared spectroscopy device. In addition, the percentage of mean propulsive velocity loss (%MPVL) was recorded using a linear transducer. The results suggested an influence of LE and training load on muscle oxygenation. A greater LE was directly associated with SmO2recT (r = 0.864), ▽%SmO2 (r = 0.873), and %MPVL (r = 0.883) and inversely with SmO2stop (r = -0.871). When the same LE was used (E1 vs. E4, E2 vs. E5, and E3 vs. E6), it was found that the stimuli with a higher load had a lower SmO2recT, ▽%SmO2, and %MPVL and a higher SmO2stop. Muscle oxygen saturation was found to be minimal (%SmO2 = 0) in stimuli with a LE greater than 60% (E3 and E6). The SmO2 variables studied in the present research could be considered as an easier and more useful method for understanding skeletal muscle fatigue during resistance training.
... To guarantee a similar movement pattern, attempts with bar-displacement variations higher than 5% were discarded [25]. Athletes performed the eccentric phase in a controlled manner, maintaining a static position for ~1 s (supporting the weight of the barbell) at the end of this phase to reduce the contribution of the rebound effect and provide more reproducible measurements [26]. ...
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The aims of this study were to compare the outcomes and provide reference data for a set of barbell mechanical parameters collected via a linear velocity transducer in 126 male sprinters (n=62), rugby (n=32), and soccer players (n=32). Bar-velocity, bar-force, and bar-power outputs were assessed in the jump-squat exercise with jump-squat height determined from bar-peak velocity. The test started at a load of 40% of the athletes’ body mass (BM) and a load of 10% of BM was gradually added until a clear decrement in the bar-power was observed. Comparisons of bar-variables among the three sports were performed using a one-way analysis of variance. Relative measures of bar-velocity, -force, and -power, and jump-squat height were significantly higher in sprinters than in rugby (difference ranging between 5 and 35%) and soccer (difference ranging between 5 and 60%) players across all loads (40-110% of BM). Rugby players exhibited higher absolute bar-power (mean difference = 22%) and bar-force (mean difference = 16%) values than soccer players, but these differences no longer existed when the data were adjusted for BM (mean difference = 2.5%). Sprinters optimized their bar-power production at significantly greater relative loads (% BM) than rugby (mean difference = 22%) and soccer players (mean difference = 25%); nonetheless, all groups generated their maximum bar-power outputs at similar bar-velocities. For the first time, we provided reference values for the jump-squat exercise for three different bar-velocity measures (i.e., mean, mean propulsive-, and peak-velocity) for sprinters, rugby, and soccer players, over a wide range of relative loads. Practitioners can use these reference values to monitor their athletes and compare them with top-level sprinters and team-sport players.
... The participants were required to perform the eccentric phase at a controlled velocity (∼0.30 to 0.50 m/s) and maintain a static position for ∼1.5 seconds at the end of this phase (ie, ∼1 cm above each participant's chest) with the aim of minimizing the contribution of the rebound effect and allowing for more reproducible measurements. 27 Then, the concentric phase was performed at the maximal intended velocity upon hearing the command. Each participant was carefully instructed to always perform the concentric phase of each repetition in an explosive manner, but throwing the bar at the end of the concentric phase was not allowed. ...
Article
Purpose: This study aimed (1) to analyze the interindividual variability in the maximal number of repetitions (MNR) performed against a given relative load (percentage of 1-repetition maximum [%1RM]) and (2) to examine the relationship between the velocity loss (VL) magnitude and the percentage of completed repetitions with regard to the MNR (%Rep), when the %1RM is based on individual load-velocity relationships. Methods: Following an assessment of 1RM strength and individual load-velocity relationships, 14 resistance-trained men completed 5 MNR tests against loads of 50%, 60%, 70%, 80%, and 90% 1RM in the Smith machine bench-press exercise. The relative loads were determined from the individual load-velocity relationship. Results: Individual relationships between load and velocity displayed coefficients of determination (R2) ranging from .986 to .998. The MNR showed an interindividual coefficient of variation ranging from 8.6% to 33.1%, increasing as the %1RM increased. The relationship between %Rep and the magnitude of VL showed a general R2 of .92 to .94 between 50% and 80% 1RM, which decreased to .80 for 90% 1RM. The mean individual R2 values were between .97 and .99 for all loading conditions. The %Rep when a given percentage of VL was reached showed interindividual coefficient of variation values ranging from 5% to 20%, decreasing as the %Rep increased in each load condition. Conclusions: Setting a number of repetitions had acceptable interindividual variability, with moderate relative loads being adjusted based on the individual load-velocity relationship. However, to provide a more homogeneous level of effort between athletes, the VL approach should be considered, mainly when using individual VL-%Rep relationships.
... Twenty recreationally active male athletes (age 23.6 ± 4.1 y, height 181.9 ± 5.8 cm, and body mass 85.8 ± 11.5 kg) visited the laboratory twice, separated by 2 weeks. On the first visit, athletes performed a standardized 1RM (one-repetition maximum) test [35] of back squats, consisting of two trials with a 3 min rest between repetitions, starting at 20 kg and progressively increasing in 15 kg increments until the mean velocity was lower than 0.7 m/s. Later, the attained load was incremented with smaller weights between 2.5 and 5 kg until the heaviest load each athlete was able to lift was considered the maximum load or 1RM. ...
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Velocity-based training is a contemporary method used by sports coaches to prescribe the optimal loading based on the velocity of movement of a load lifted. The most employed and accurate instruments to monitor velocity are linear position transducers. Alternatively, smartphone apps compute mean velocity after each execution by manual on-screen digitizing, introducing human error. In this paper, a video-based instrument delivering unattended, real-time measures of barbell velocity with a smartphone high-speed camera has been developed. A custom image-processing algorithm allows for the detection of reference points of a multipower machine to autocalibrate and automatically track barbell markers to give real-time kinematic-derived parameters. Validity and reliability were studied by comparing the simultaneous measurement of 160 repetitions of back squat lifts executed by 20 athletes with the proposed instrument and a validated linear position transducer, used as a criterion. The video system produced practically identical range, velocity, force, and power outcomes to the criterion with low and proportional systematic bias and random errors. Our results suggest that the developed video system is a valid, reliable, and trustworthy instrument for measuring velocity and derived variables accurately with practical implications for use by coaches and practitioners.
... Esses procedimentos são realizados assumindo a existência de um número médio aproximado de repetições máximas por série que podem ser realizadas com cada percentual de 1RM, de acordo com o tipo de exercício e o nível de treinamento do sujeito [9,10,12], e, portanto, considera-se que um certo número de repetições máximas representa uma intensidade relativa específica (%1RM). Embora essa abordagem elimine a necessidade de realizar um teste direto de 1RM, também não está isenta de desvantagens: Intensidade de treinamento como velocidade de execução na ação concêntrica (VMP da 1ª repetição) Atualmente, como resultado dos avanços tecnológicos que permitem medir a velocidade de execução em exercícios com pesos livres, há a possibilidade de determinar/estimar, com alto grau de precisão, a intensidade relativa (%1RM) que representa a carga absoluta usada na sessão de treinamento, a partir da primeira (ou mais rápida) repetição da série, sempre executada a máxima velocidade possível [5,[25][26][27][28], tudo através de equações de regressão específicas para cada exercício. Isso ocorre porque a velocidade média propulsiva da repetição mais rápida da série está intrinsecamente associada à magnitude relativa da carga (%1RM), e, portanto, cada %1RM tem sua própria velocidade [5]. ...
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Determinação e controle da intensidade e volume do treinamento de força na pesquisa nas ciências do exercício e sua aplicação. Resumo Nos estudos iniciais, que documentaram os efeitos positivos do treinamento com pesos e a execução de esforços musculares repetidos [1-3], o propósito da ciência de conhecer a melhor maneira de definir, controlar e dosar o treinamento de força tem sido uma das questões que concentraram o maior interesse e esforço. Trata-se de uma questão extremamente importante, pois os resultados originários dos trabalhos científicos de maior qualidade devem possibilitar a continuação da geração do corpo de conhecimento que ajuda a melhorar a metodologia do treinamento e, portanto, as participações na prática dos profissionais. Para que isso seja cumprido, os estudos científicos devem ter, entre outros atributos, um método preciso de determinação e controle das variáveis que definem o estímulo do treinamento proposto, a fim de verificar a relação entre ele e os efeitos produzidos. No entanto, se isso não acontecer, pesquisadores e profissionais do treinamento correm o risco de tomar decisões sobre a configuração dos estímulos (manipulação das variáveis da carga) com base em conclusões científicas "falsas" ou incertas, na melhor das hipóteses. Palavras-chave: Variáveis, dosagem, quantificação, carga, intensidade, volume.
... El test inicia con una carga de 10kg con la que se realizan cuatro repeticiones, seguidamente se efectúan incrementos progresivos del 5kg y con ellos se ejecutan tres repeticiones con cada peso, hasta que la VMP alcanzada era inferior a 0,50 m·s -1 (Pallares, Sanchez-Medina, Perez, De La Cruz-Sanchez, & Mora-Rodriguez, 2014). A partir de ese momento, los incrementos fueron de 1 a 2 kg y se realizan dos repeticiones con cada peso, hasta cuando las participantes eran incapaces de realizar la extensión a 180° y la VMP era inferior o igual a 0.20ms. ...
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Objetivo: Comparar la tasa de fuerza relativa (TFR) con distintos indicadores de fuerza en mujeres jóvenes. Métodos: Se evaluaron a 146 mujeres que se distribuyeron en tres grupos de acuerdo con los resultados de la TFR obtenida en el ejercicio de sentadilla y se compararon los resultados obtenidos en las pruebas de Fuerza prensil de la mano derecha e izquierda (FPMD- FPMI), Fuerza isométrica miembros inferiores (FIMI), Fuerza máxima de pecho (FMP), Fuerza máxima en sentadilla (FMS) Velocidad de desplazamiento sobre treinta metros (V30), altura del salto en (CMJ), potencia de pedaleo (PP) y la velocidad media propulsiva de miembros superiores e inferiores (VMPMS-VMPMI) obtenida al 50%, 60%, 70% y 80% de una repetición máxima en sentadilla. Resultados: Se observaron diferencias significativas (p?0,01) entre los grupos en la FMS, CMJ, V30, VMP y PP, y la mayoría de las variables presentaban la diferencia entre el G1 y G3 (p?0,01).
... After a ~ one-second pause, a verbal signal was given by a researcher and the subjects performed the concentric phase of the movement as fast as possible. The stop on the chest was used to minimize bouncing on the chest and, thus, to standardize the technique (Pallarés et al. 2014). The bar needed to stay in the hands of the subject during the whole exercise. ...
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Purpose Men and women typically display different neuromuscular characteristics, force–velocity relationships, and differing strength deficit (upper vs. lower body). Thus, it is not clear how previous recommendations for training with velocity-loss resistance training based on data in men will apply to women. This study examined the inter-sex differences in neuromuscular adaptations using 20% and 40% velocity-loss protocols in back squat and bench press exercises. Methods The present study employed an 8-week intervention (2 × week) comparing 20% vs. 40% velocity-loss resistance training in the back squat and bench press exercises in young men and women (~ 26 years). Maximum strength (1-RM) and submaximal-load mean propulsive velocity (MPV) for low- and high-velocity lifts in squat and bench press, countermovement jump and vastus lateralis cross-sectional area were measured at pre-, mid-, and post-training. Surface EMG of quadriceps measured muscle activity during performance tests. Results All groups increased 1-RM strength in squat and bench press exercises, as well as MPV using submaximal loads and countermovement jump height ( P < 0.05). No statistically significant between-group differences were observed, but higher magnitudes following 40% velocity loss in 1-RM ( g = 0.60) and in low- ( g = 1.42) and high-velocity ( g = 0.98) lifts occurred in women. Training-induced improvements were accompanied by increases in surface EMG amplitude and vastus lateralis cross-sectional area. Conclusion Similar increases in strength and power performance were observed in men and women over 8 weeks of velocity-based resistance training. However, some results suggest that strength and power gains favor using 40% rather than 20% velocity loss in women.
... The bar should be lowered slowly and in a controlled fashion towards the chest, slightly above the nipples. The bar should then be held in this position for approximately 1.5 s, and supported over the chest, to eliminate the rebound effect and improve the consistency of repetitions [22]. The order to move into the concentric phase was given verbally by a researcher counting down to 1.5 s from the beginning of the eccentric phase. ...
Article
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Citation: Maté-Muñoz, J.L.; Garnacho-Castaño, M.V.; Hernández-Lougedo, J.; Maicas-Pérez, L.; Notario-Alonso, R.; Da Silva-Grigoletto, M.E.; García-Fernández, P.; Heredia-Elvar, J.R. Analysis of the Use and Applicability of Different Variables for the Prescription of Relative Intensity in Bench Press Exercise. Biology 2022, 11, 336. https://
... ). These variables have been shown as highly reliable,36,37 and they provide a much more comprehensive analysis of traininginduced changes across the load(force)-velocity spectrum rather than simply focusing on a 1RM strength value. A linear velocity transducer (T-FORCE Dynamic Measurement System; Ergotech Consulting Ltd., Murcia, Spain) and its associated software (version 3.70) automatically calculated and registered the kinematics of every repetition and provided auditory and visual feedback. ...
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This study aimed to compare the effects of three resistance training (RT) programs differing in the magnitude of velocity loss (VL) allowed in each exercise set: 10%, 30% or 45% on changes in strength, vertical jump, sprint performance and EMG variables. Thirty‐three young men were randomly assigned into three experimental groups (VL10%, VL30% and VL45%; n=11 each) that performed a velocity‐based RT program for 8 weeks using only the full‐squat exercise (SQ). Training load (55‐70% 1RM), frequency (2 sessions/week), number of sets (3) and inter‐set recovery (4 min) were identical for all groups. Running sprint (20 m), countermovement jump (CMJ), 1RM, muscle endurance and EMG during SQ were assessed pre‐ and post‐training. All groups showed significantly (VL10%: 6.4‐58.6%; VL30%: 4.5‐66.2%; VL45%: 1.8‐52.1%; p<0.05‐0.001) improvements in muscle strength and muscle endurance. However, a significant group×time interaction (p<0.05) was observed in CMJ, with VL10% showing greater increments (11.9%) than VL30% and VL45%. In addition, VL10% resulted in greater percent change in sprint performance than the other two groups (VL10%: ‐2.4%; VL30%: ‐1.8%; VL45%: ‐0.5%). No significant changes in EMG variables were observed for any group. RT with loads of 55‐70% 1RM characterized by a low velocity loss (VL10%) provides a very effective and efficient training stimulus since it yields similar strength gains and greater improvements in sports‐related neuromuscular performance (jump and sprint) compared to training with higher velocity losses (VL30%, VL45%). These findings indicate that the magnitude of VL reached in each exercise set considerably influences the observed training adaptations.
... The stance width and foot position were individually adjusted and carefully replicated on every lift. From this position, the participants were required to descend until making contact with the bench and then to perform the concentric phase of the movement in an explosive manner [29,30]. The height of the bench was individually selected and allowed each participant to descend with the hips below the knee line, according to the rules of the International Powerlifting Federation [31]. ...
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Although velocity control in resistance training is widely studied, its utilization in eliciting post-activation performance enhancement (PAPE) responses receives little attention. Therefore, this study aimed to evaluate the effectiveness of heavy-loaded barbell squats (BS) with velocity loss control conditioning activity (CA) on PAPE in subsequent countermovement jump (CMJ) performance. Sixteen resistance-trained female volleyball players participated in this study (age: 24 ± 5 yrs.; body mass: 63.5 ± 5.2 kg; height: 170 ± 6 cm; relative BS one-repetition maximum (1RM): 1.45 ± 0.19 kg/body mass). Each participant performed two different conditions: a set of the BS at 80% 1 RM with repetitions performed until a mean velocity loss of 10% as the CA or a control condition without CA (CNTRL). To assess changes in jump height (JH) and relative mean power output (MP), the CMJ was performed 5 min before and throughout the 10 min after the CA. The two-way analysis of variance with repeated measures showed a significant main effect of condition (p = 0.008; η2 = 0.387) and time (p < 0.0001; η2 = 0.257) for JH. The post hoc test showed a significant decrease in the 10th min in comparison to the value from baseline (p < 0.006) for the CNTRL condition. For the MP, a significant interaction (p = 0.045; η2 = 0.138) was found. The post hoc test showed a significant decrease in the 10th min in comparison to the values from baseline (p < 0.006) for the CNTRL condition. No significant differences were found between all of the time points and the baseline value for the CA condition. The CA used in the current study fails to enhance subsequent countermovement jump performance in female volleyball players. However, the individual analysis showed that 9 out of the 16 participants (56%) responded positively to the applied CA, suggesting that the PAPE effect may be individually dependent and should be carefully verified before implementation in a training program.
... In order to execute the strength exercises with maximal concentric velocity, the participants performed rapid movements without any instructions regarding the pauses between the concentric and eccentric phase of each repetition. It was previously suggested that imposing a pause between eccentric and concentric movements would increase the reliability of acceleration measurements using a smartwatch [30]. Thus, it is possible that clear instructions to the pauses may have helped to lower the coefficient of variation in the smartwatch data readings, thereby increasing the accuracy in exercise recognition, repetition counting and successful attempts to predict 1RM. ...
Article
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The goal of this study was to assess the validity, reliability and accuracy of a smartwatch-based workout analysis application in exercise recognition, repetition count and One Repetition Maximum (1RM) prediction in the strength training-specific setting. Thirty recreationally trained athletes performed four consecutive sets of barbell deadlift, barbell bench press and barbell back squat exercises with increasing loads from 60% to 80% of their estimated 1RM with maximum lift velocity. Data was measured using an Apple Watch Sport and instantaneously analyzed using an iOS workout analysis application called StrengthControl. The accuracies in exercise recognition and repetition count, as well as the reliability in predicting 1RM, were statistically analyzed and compared. The correct strength exercise was recognised in 88.4% of all the performed sets (N = 363) with accurate repetition count for the barbell back squat (p = 0.68) and the barbell deadlift (p = 0.09); however, repetition count for the barbell bench press was poor (p = 0.01). Only 8.9% of attempts to predict 1RM using the StrengthControl app were successful, with failed attempts being due to technical difficulties and time lag in data transfer. Using data from a linear position transducer instead, significantly different 1RM estimates were obtained when analysing repetition to failure versus load-velocity relationships. The present results provide new perspectives on the applicability of smartwatch-based strength training monitoring to improve athlete performance.
... Currently, because of advances in technology that allow the execution velocity measurement in exercises with free weights, there is the possibility of determining/estimating, with a high degree of precision, the relative intensity (%1RM) that represents the absolute load lifted from the first (or fastest) repetition of the set, always performed at the maximum possible velocity [5,[25][26][27][28], all this through specific regression equations for each exercise. This result occurs because the mean propulsive velocity of the fastest repetition of the set is intrinsically associated with the relative load magnitude (%1RM), and therefore each %1RM has its velocity [5]. ...
Article
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Nos estudos iniciais, que documentaram os efeitos positivos do treinamento com pesos e a execução de esforços musculares repetidos, o propósito da ciência de conhecer a melhor maneira de definir, controlar e dosar o treinamento de força tem sido uma das questões que concentraram o maior interesse e esforço. Trata-se de uma questão extremamente importante, pois os resultados originários dos trabalhos científicos de maior qualidade devem possibilitar a continuação da geração do corpo de conhecimento que ajuda a melhorar a metodologia do treinamento e, portanto, as participações na prática dos profissionais. Para que isso seja cumprido, os estudos científicos devem ter, entre outros atributos, um método preciso de determinação e controle das variáveis que definem o estímulo do treinamento proposto, a fim de verificar a relação entre ele e os efeitos produzidos. No entanto, se isso não acontecer, pesquisadores e profissionais do treinamento correm o risco de tomar decisões sobre a configuração dos estímulos (manipulação das variáveis da carga) com base em conclusões científicas "falsas" ou incertas, na melhor das hipóteses.
... This position was recorded for each subject and marked so that an audible signal was given by the evaluator when reaching that individual position. A momentary pause (~1 s) was imposed between the eccentric and the concentric phase to eliminate the use of elastic energy on the eccentric movement and to obtain more stable and reliable measurements (Pallares, Sanchez-Medina, Perez, De La Cruz-Sanchez, & Mora-Rodriguez, 2014). If the execution was not correct or the displacement range was not adequate (at the discretion of the evaluators), a new series was performed with the same absolute load after the corresponding rest period. ...
Article
The aims of this study were: i) to analyze the load-velocity relationship in the bilateral leg-press exercise in female breast cancer survivors, ii) to assess whether mean velocity (MV) or peak velocity (PV) show stronger relationship with the relative load, and iii) to examine whether linear (LA) or polynomic (PA) adjustment predict the velocities associated with each %1RM with greater precision. Twenty-two female breast cancer survivors (age: 50.2±10.8 years, weight: 69.6±15.2 kg, height: 160.51±5.25 cm) completed an incremental load test until 1RM in the bilateral leg-press exercise. The MV and the PV of the concentric phase were measured in each repetition using a linear velocity transducer, and were analyzed by regression models using LA and PA. A very close relationship of MV (R²=0.924; p<0.0001; SEE=0.08m.s⁻¹ by LA, and R²=0.952; p<0.0001; SEE=0.063 m.s⁻¹ by PA) and PV (R²=0.928; p<0.0001; SEE=0.119 m.s⁻¹ by LA and R²=0.941; p<0.0001; SEE=0.108 m.s⁻¹ by PA) with %1RM were observed. The MV of 1RM was 0.24±0.03 m·s⁻¹, whereas the PV at 1RM was 0.60±0.10 m.s⁻¹. A comprehensive analysis of the bilateral leg-press load-velocity relationship in breast cancer survivors is presented. The results suggest that MV is the most recommendable velocity variable to prescribe the relative load during resistance training, and that the PA presents better accuracy to predict velocities associated with each %1RM, although LA is sufficiently valid to use this model as an alternative to the quadratic model. The implications for resistance training in breast cancer are discussed.
... Each participant was instructed to lower the barbell to the chest above the nipples in a slow and controlled manner, and then wait there in an alert state until instructed to lift by an experienced evaluator. A pause lasting about 1.5 s was applied between the eccentric phase and the concentric phase to minimize the impact of the rebound effect and achieve more repeatable and consistent measurements [19]. The participants were not allowed to bounce the barbell from their chest or lift their shoulders or torso off the bench. ...
Article
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Abstract: The aim of this research was to verify whether the application of percussion therapy during inter-set rest periods increases the number of repetitions performed before reaching a 30% velocity loss threshold during a bench press exercise. Methods: Twenty-four male university students participated in this study (24.3 ± 1.3 years; 77.5 ± 8.3 kg; 177.0 ± 5.6 cm; 24.7 ± 2.6 kg·m−2). Participants were randomized into two groups: a percussion therapy group (PTG) and a control group (CG). They performed 4 sets at 70% of a one-repetition maximum before reaching a 30% velocity loss threshold with an inter-set recovery of 3 min. Results: The PTG performed a greater total number of repetitions compared to the CG (44.6 ± 4.8 vs. 39.5 ± 6.8; p = 0.047; ES = 0.867). No differences were observed for the different movement velocity variables and fatigue control (p > 0.05). Conclusions: Percussion therapy is an effective method to delay the loss of movement velocity in the bench press exercise.
... Performing a 2-second pause prior to the concentric portion of a lift has previously been shown to improve reliability during isoinertial strength testing. 17 Strong verbal encouragement and velocity feedback were provided, because this has been shown to improve athlete motivation and performance in strength tasks that involve measuring movement velocity. 18 The fastest of the 2 repetitions was used for further analysis. ...
Article
Purpose: To compare resistance training using a velocity loss threshold with training to repetition failure on upper-body strength parameters in professional Australian footballers. Methods: A total of 26 professional Australian footballers (23.9 [4.2] y, 189.9 [7.8] cm, 88.2 [8.8] kg) tested 1-repetition-maximum strength (FPmax) and mean barbell velocity at 85% of 1-repetition maximum on floor press (FPvel). They were then assigned to 2 training groups: 20% velocity loss threshold training (VL; n = 12, maximum-effort lift velocity) or training to repetition failure (TF; n = 14, self-selected lift velocity). Subjects trained twice per week for 3 weeks before being reassessed on FPmax and FPvel. Training volume (total repetitions) was recorded for all training sessions. No differences were present between groups on any pretraining measure. Results: The TF group significantly improved FPmax (105.2-110.9 kg, +5.4%), while the VL group did not (107.5-109.2 kg, +1.6%) (P > .05). Both groups significantly increased FPvel (0.38-0.46 m·s-1, +19.1% and 0.37-0.42 m·s-1, +16.7%, respectively) with no between-groups differences evident (P > .05). The TF group performed significantly more training volume (12.2 vs 6.8 repetitions per session, P > .05). Conclusions: Training to repetition failure improved FPmax, while training using a velocity loss threshold of 20% did not. Both groups demonstrated similar improvements in FPvel despite the VL group completing 45% less total training volume than the TF group. The reduction in training volume associated with implementing a 20% velocity loss threshold may negatively impact the development of upper-body maximum strength while still enhancing submaximal movement velocity.
... Esto puede deberse a la familiarización con estos gestos fuera de las condiciones del experimento donde las acciones cotidianas de la población analizada ocurren de tal manera que la fase de RE es predominantemente excéntrica, mientras que la contracción de RI es principalmente concéntrica . Sin embargo, los límites de acuerdo son más amplios en una fase excéntrica como los resultados obtenidos en (Pallarés, Sánchez-Medina, Pérez, De La Cruz-Sánchez, & Mora-Rodriguez, 2014), probando que una parada entre fases produce una mejor adaptación de los sujetos a las condiciones de evaluación. El personal de ámbito clínico y entrenadores deben tener en cuenta estos resultados para individualizar los protocolos de evaluación según el tipo de población y los objetivos pretendidos, ya sean deportistas de elite o poblaciones con dolor crónico en el hombro. ...
Thesis
Introduction: Overhead throwing is an essential skill in sports such as handball, water polo, baseball and so on. For athletes in these sports, maximal strength, power and throwing velocity are some of the most important variables for success. If a review of the literature is made, it can be observed that all types of training methodologies have been used, ranging from the use of more generalised exercises to more specific methods that attempt to imitate the throwing technique. In recent years, with the rise of different technologies for the measurement and objective control of variables related to strength training, it has become possible to implement stimuli such as eccentric overload, intra-repetition variability, or isokinetic movements into strength programs. But little is known about the use of isokinetic devices for the evaluation and training of overhead throwing. Objective: To determine the applicability of isokinetic assessments and training (using one of these multi-joint isokinetic dynamometers) in training for throwing velocity improvement, and subsequently make recommendations for their use. Methodology: The first of the studies included in this research is a systematic review and meta-analysis while the rest of the studies correspond to cross-sectional designs of a quantitative nature. The second study involved 32 subjects (age 21.46 ± 2.1 years) to determine the reliability of a shoulder rotator strength test using a FEMD. In the third phase, 20 handball players (age 19.28±2.55 years) participated to analyse if any correlation between the internal rotation strength of the throwing arm with the ball exit velocity in a supporting throw. In the last study, 14 female handball players (21.2±2.7 years) were subjected to different pre-activation protocols in the upper body to see if there was a subsequent potentiation in throwing speed. Results: (I) A total of 16 studies with 424 subjects were included in the meta-analysis to assess the effect of strength training on throwing velocity. The effect size for all population groups showed that there is a large improvement in throwing velocity after a training programme (ES 1.10; 95% CI 0.64 - 1.57; p < 0.00001). (II) High to excellent reliability was found for RI and RE in concentric and eccentric strength measurements, irrespective of the velocity used (ICC: 0.81-0.98, CV: 5.12-8.27% SEM: 4.06-15.04N). Concentric movements were more reliable than eccentric movements due to the possible familiarity of the population with this type of stimuli. (III) No correlation was found between any of the dominant arm RI strength variables and throwing in handball support. (IV) No significant differences were found for either method (intra-repetition variable resistance: p = 0.194, isometrics: p = 0.596). Even so, individualised analysis showed that 86% of the sample increased throwing speed with the variable intra-repetition resistance method, while 93% of the sample increased throwing speed with the isometric method. Conclusions: After the completion of this thesis it can be concluded that the FEMD is a reliable and useful device for the evaluation and training of athletes who perform the technical gesture of the overhead throw.
... The BP was performed imposing a momentary pause (~1.5 s) at the chest between the eccentric and concentric actions to minimize the contribution of the rebound effect and allow for more reproducible measurements. 12 The SQ was performed with subjects starting from the upright position with the knees and hips fully extended, feet approximately shoulder-width apart and the 8 barbell resting across the back at level of the acromion. Each subject descended at a controlled pace (~0.50 m·s -1 ) until the top of the thighs were below the horizontal plane, then immediately reversed motion and ascended back to the upright position. ...
Article
Background: To analyze the short-term response to three resistance training (RT) protocols: RT protocol leading to failure (MaxRep), half-maximal repetitions protocol in untrained condition (U-HalfRep), and half-maximal repetitions protocol in trained condition (T-HalfRep). Methods: Ten males without RT experience performed 3 sets of 5 vs. 10 repetitions with their estimated 10RM load, U-HalfRep vs. MaxRep, in the bench press and squat exercises before a 10-week RT period. After the RT period, the half-maximal repetitions protocol was repeated (T-HalfRep). Mechanical performance (jump height, and velocity against the 1 m·s-1 load) and biochemical plasma profile (testosterone, cortisol, growth hormone, prolactin, IGF-1 and creatine kinase) were assessed at several time-points from 24 h pre- to 48 h postexercise. Results: MaxRep resulted in greater reductions and slower recovery in mechanical performance compared to half-maximal repetitions protocols. Moreover, U-HalfRep resulted in greater jump performance impairment than T-HalfRep up to 48 h-post. MaxRep also showed greater acute increments in growth hormone and prolactin. U-HalfRep and MaxRep induced higher creatine kinase levels. Conclusions: The MaxRep resulted in greater fatigue accumulation and slower recovery, higher hormonal response and muscle damage. The same athletes suffered slower recovery and higher muscle damage before training compared to after training despite using the same relative stimulus.
... A partir dessa posição, os participantes desceram em movimento controlado até que a prega inguinal atingisse (ponto B) o mesmo plano horizontal da borda superior da patela [10,22]. Após uma pausa momentânea (~1,5 s), eles subiram de volta à posição ereta, mantendo uma postura de tronco ereta [23]. ...
Article
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Objetivos: Os objetivos deste estudo foram: 1) comparar a relação carga-velocidade estimada pelo método de dois pontos entre homens e mulheres destreinados durante o exercício agachamento paralelo (BS) e 2) comparar o perfil carga-velocidade encontrado em nosso estudo com os perfis de carga-velocidade relatados na literatura científica para indivíduos treinados. Além disso, comparar a velocidade de 1RM medida com a velocidade de 1RM predita pelo método de dois pontos no exercício BS em indivíduos destreinados. Métodos: Setenta e seis indivíduos destreinados (38 homens (22,7 ± 4,4 anos; 174,9 ± 6,8 cm; 76,1 ± 14,9 kg) e 38 mulheres (24,7 ± 4,3 anos; 159,1 ± 6,0 cm; 64,7 ± 13,3 kg) realizaram um teste de uma repetição máxima e um teste progressivo de duas cargas com 20% e 70% 1RM para estimar suas relações carga-velocidade. Resultados: Os principais resultados revelaram que 1) a velocidade média propulsiva e a velocidade média atingida em cada carga relativa foram diferentes entre homens e mulheres (p < 0,05). No entanto, a velocidade de 1RM medida não foi significativamente diferente entre eles. Homens destreinados forneceram uma relação carga-velocidade mais acentuada do que as mulheres. Descobrimos que 2) os indivíduos destreinados de nosso estudo apresentaram um perfil carga-velocidade diferente dos indivíduos treinados dos estudos da literatura científica. Além disso, 3) a velocidade de 1RM medida foi menor do que a velocidade de 1RM predita (p < 0,05). Conclusão: Esses resultados sugerem que a relação carga-velocidade é dependente do sexo e treinamento, e que o método de dois pontos usando 20% e 70% 1RM não seria confiável para estimar a relação carga-velocidade no exercício agachamento paralelo em homens e mulheres destreinados. Palavras-chave: exercício; mensuração da velocidade; força muscular.
... They were instructed to lower the bar to the chest just above the nipples in a controlled way and, after approximately 1.0 seconds of pause, to start the concentric phase of the movement as fast as possible. The pause at the chest between the eccentric and concentric actions occurred to minimize the contribution of the rebound effect and thus allow for more reproducible, consistent measurements [26]. The subjects were not allowed to bounce the bar off their chest nor to raise their shoulders or trunk off the bench [24]. ...
Article
Background and objective: The purpose of this study was to investigate the effect of specific warm-up on squat and bench press resistance training. Methods: Thirty-four resistance-trained males (23.53 ± 2.35 years) participated in the current study. Among these, 12 were evaluated in the squat and 22 in the bench press. After determining the maximal strength load (1RM), each participant performed a training set (3 × 6 repetitions) with 80% 1RM (training load) after completing a specific warm-up and without warming up, in random order. The warm-up comprised 2 × 6 repetitions with 40% and 80% of the training load, respectively. Mean propulsive velocity, velocity loss, peak velocity, mechanical power, work, heart rate and ratings of perceived exertion were assessed. Results: The results showed that after the warm-up, the participants were able to perform the squat and bench press at a higher mean propulsive velocity in the first set (squat: 0.68 ± 0.05 vs. 0.64 ± 0.06 m⋅s-1, p = 0.009, ES = 0.91; bench press: 0.52 ± 0.06 vs. 0.47 ± 0.08 m⋅s-1, p = 0.02, ES = 0.56). The warm-up positively influenced the peak velocity (1.32 ± 0.12 vs. 1.20 ± 0.11 m⋅s-1, p = 0.001, ES = 1.23) and the time to reach peak velocity (593.75 ± 117.01 vs. 653.58 ± 156.53 ms, p = 0.009, ES = 0.91) during the squat set. Conclusion: The specific warm-up seems to enhance neuromuscular actions that enable a higher movement velocity during the first training repetitions and to allow greater peak velocities in less time.
... The bar was required to remain in contact with the back and shoulders at all times. From this position, they were required to descend until making contact the upper leg was horizontal [30,31]. ...
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Background: Resistance training is a significant part of ice-hockey players’ conditioning, where optimal loading should ensure strength development and proper recovery. Therefore, this study aimed to compare the acute physiological responses to fast and medium movement tempo resistance exercises in ice-hockey players. Methods: Fourteen ice-hockey players (26.2 � 4.2 years; 86.4 � 10.2 kg; squat one repetition maximum (1RM) = 130.5 � 18.5) performed five sets of the barbell squat and barbell bench press at 80% 1RM until failure in a crossover design one week apart using either 2/0/2/0 or 6/0/2/0 (eccentric/isometric/concentric/isometric) tempo of movement. The blood samples to evaluate the concentration of cortisol, testosterone, insulin-like growth factor 1 (IGF-1), and growth hormone (hGH) were taken before exercise, 3 min after the last set of the squat exercise, 3 min after the last set of the bench press exercise, and after 30 min of recovery. Results: The 2/0/2/0 tempo resulted in a higher number of repetitions (p < 0.001) and lower time under tension (p < 0.001) in the squat and bench press exercises compared to the 6/0/2/0 movement tempo. The endocrine responses to exercise were significantly higher during the 2/0/2/0 compared to the 6/0/2/0 movement tempo protocol for IGF-1, hGH, and cortisol (p < 0.01). There were no differences in testosterone responses between exercises performed with fast and medium movement tempos. Conclusion: Fast eccentric tempo induced higher cortisol, IGF-1, and hGH responses compared to the medium tempo. Therefore, fast eccentric movement tempo seems to be more useful in eliciting training stimulus than medium eccentric tempo during resistance training in ice-hockey players. However, future studies are needed to confirm our findings.
Article
Velocity-based training (VBT) is gaining popularity in strength and conditioning due to multiple practical advantages for auto-regulating and individualizing training volume and load on a day-to-day basis. Because the load-velocity relationship varies among exercises, the knowledge of particular equations is indispensable to effectively implement the VBT. The aim of this study was to determine the complete load- and power-velocity profile of the deadlift exercise to provide practical equations and normative values for resistance training coaches and practitioners. Twenty strength-trained men performed a progressive loading test at maximal intended velocity to determine their one-repetition maximum (1RM). Mean (MV), mean propulsive (MPV) and peak velocity (PV) were measured during the concentric phase. Both MV and MPV showed a very close relationship to %1RM (R² = 0.971 and R² = 0.963) with a low error of estimation (SEE = 0.08 and 0.09 m·s⁻¹), which was maintained throughout the wide breadth of velocities. PV showed the poorest results (R² = 0.958, SEE = 0.15 m·s⁻¹). MV attained with the 1RM was 0.24±0.03 m·s⁻¹ and consistent between participants with different relative strengths. The load that maximized the power output was identified at ∼60% 1RM. In contrast to what was observed in velocity, power outcomes showed poor predictive capacity to estimate %1RM. Hence, the use of velocity-based equations is advisable to monitor athletes’ performance and adjust the training load in the deadlift exercise. This finding provides an alternative to the demanding, time-consuming and interfering 1RM tests, and allows the use of the deadlift exercise following the VBT principles.
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This study investigated the inter- and intra-device agreement of four new devices marketed for barbell velocity measurement. Mean, mean propulsive and peak velocity outcomes were obtained for bench press and full squat exercises along the whole load-velocity spectrum (from light to heavy loads). Measurements were simultaneously registered by two linear velocity transducers T-Force, two linear position transducers Speed4Lifts, two smartphone video-based systems My Lift, and one 3D motion analysis system STT. Calculations included infraclass correlation coefficient (ICC), Bland-Altman Limits of Agreement (LoA), standard error of measurement (SEM), smallest detectable change (SDC) and maximum errors (MaxError). Results were reported in absolute (m/s) and relative terms (%1RM). Three velocity segments were differentiated according to the velocity-load relationships for each exercise: heavy (≥ 80% 1RM), medium (50% < 1RM < 80%) and light loads (≤ 50% 1RM). Criteria for acceptable reliability were ICC > 0.990 and SDC < 0.07 m/s (~5% 1RM). The T-Force device shown the best intra-device agreement (SDC = 0.01–0.02 m/s, LoA <0.01m/s, MaxError = 1.3–2.2%1RM). The Speed4Lifts and STT were found as highly reliable, especially against lifting velocities ≤1.0 m/s (Speed4Lifts, SDC = 0.01–0.05 m/s; STT, SDC = 0.02–0.04 m/s), whereas the My Lift app showed the worst results with errors well above the acceptable levels (SDC = 0.26–0.34 m/s, MaxError = 18.9–24.8%1RM). T-Force stands as the preferable option to assess barbell velocity and to identify technical errors of measurement for emerging monitoring technologies. Both the Speed4Lifts and STT are fine alternatives to T-Force for measuring velocity against high-medium loads (velocities ≤ 1.0 m/s), while the excessive errors of the newly updated My Lift app advise against the use of this tool for velocity-based resistance training.
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Background. This study aimed to determine the reliability of the velocity achieved during the last repetition of sets to failure (Vlast) and the association of Vlast with the velocity of the 1-repetition maximum (V1RM) during the paused and touch-and-go bench press (BP) exercises performed in a Smith machine. Methods. Ninety-six healthy men participated in this study that consisted of two testing sessions. A single BP variant (paused BP or touch-and-go BP) was evaluated on each session in a randomized order. Each session consisted of an incremental loading test until reaching the 1RM, followed by two sets of repetitions to failure against a load ranging from 75-90% of 1RM. Results. The reliability of Vlast was unacceptable for both BP variants (CV > 18.3%, ICC < 0.60). The correlations between V1RM and Vlast were small for the paused BP (r = 0.18) and moderate for the touch-and-go BP (r = 0.37). Conclusions. Although these results suggest that Vlast could be a better indicator of the minimal velocity threshold than V1RM, the low reliability of Vlast and the similar values of Vlast for both BP variants suggest that a standard V1RM should be used to estimate the 1RM from the individualized load-velocity relationship.
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This study aimed to compare the reliability and magnitude of velocity variables between 3 variants of the bench press (BP) exercise in participants with and without BP training experience. Thirty males, 15 with and 15 without BP experience, randomly performed 3 variants of the BP on separate sessions: (I) concentric-only, (II) fasteccentric and (III) controlled-eccentric. The mean velocity (MV) and maximum velocity (Vmax) of the concentric phase were collected against 3 loads (≈30%1RM, 50%1RM, and 75%1RM) with a linear velocity transducer. Reliability was high regardless of the variable, BP variant, and load (coefficient of variation [CV] ≤ 4.47%, intraclass correlation coefficient [ICC] ≥ 0.87). The comparison of the CVs suggested a higher reliability for the fast-eccentric BP (8 out of 12 comparisons), followed by the concentric-only BP (5 out of 12 comparisons), and finally the controlled-eccentric BP (never provided a higher reliability). No differences in reliability were observed between experienced (CV ≤ 4.71%; ICC ≥ 0.79) and non-experienced (CV ≤ 6.29%; ICC ≥ 0.76) participants. The fast-eccentric BP provided the highest MV (p < 0.05) and no significant differences were observed for Vmax. These results support the assessment of movement velocity during the fast-eccentric BP even in participants without experience.
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This study aimed to compare the within-session reliability and magnitude of velocity variables recorded against a range of submaximal loads during the bench press (BP) exercise performed in a Smith machine using different grip widths. Sixteen physically active men (BP one-repetition maximum [1RM] relative to body mass = 1.01±0.19 kg.kg-1) were randomly tested on 4 sessions using a close grip width (100% of biacromial width), medium grip width (150% of biacromial width), wide grip width (200% of biacromial width), and self-selected grip width (176±17% of biacromial width). Mean velocity (MV), maximum velocity (Vmax), and vertical displacement were recorded with a linear velocity transducer against the 35%1RM, 55%1RM, and 75%1RM. The main findings revealed that (I) the self-selected was the only grip width with an acceptable reliability for all loads and velocity variables (CV 7.56%; ICC 0.82), (II) the medium grip width provided the highest reliability for MV (CV ratio 1.20), while a comparable reliability was observed for Vmax using the close, medium and self-selected grip widths (CV ratio 1.08), (III) the Vmax showed the highest reliability for all grip widths (CV ratio =1.68), and (IV) the MV and vertical displacement of the barbell were generally higher for narrow grip widths (close and medium) compared to the wide and self-selected grip widths, while no significant differences between the grip widths were observed for Vmax (p >0.05). Taken together, we recommend the assessment of Vmax using a self-selected grip width during the routine testing of BP performance against submaximal loads.
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This study aimed to analyze the influence of range of motion (ROM) on main biomechanical parameters of the bench press (BP) exercise: i) load-velocity relationship by mean (MV) and mean propulsive velocity (MPV), ii) one-repetition maximum strength (1RM); iii) contribution of the propulsive and braking phases, and iv) presence of the sticking region key parameters (first peak barbell velocity: Vmax1, minimum velocity: Vmin and second peak barbell velocity: Vmax2). Forty-two strength-trained males performed a progressive loading test, starting at 20 kg and gradually increasing the load in 10 kg until MPV ≤ 0.50 m·s-1 and 5 down to 2.5 kg until 1RM, in three different ROMs: full ROM (BPFULL), two-thirds (BP2/3) and one-third (BP1/3). While significant differences were detected in the velocity attained against loads between 30-95% 1RM (BPFULL, BP2/3 and BP1/3, p < 0.05), both MV and MPV showed a very close relationship to %1RM for the three BP variations (R2 = 0.935-0.966). The contribution of the braking phase decreased progressively until it completely disappeared at the 80%, 95% and 100% 1RM loads in BP1/3, BP2/3 and BPFULL, respectively. The 1RM increased as the ROM decreased (BPFULL < BP2/3 < BP1/3, p < 0.05). Despite the three bio-mechanical parameters that define the sticking region on the velocity time curves were only observed in BPFULL variation, in 54.5% of the cases the subjects started their BP2/3 displacement before reaching the position at which the Vmin occurs in their BPFULL exercise. The complete or partial presence of the sticking region during the concentric action of the lift seems to underlie the differences in the 1RM strength, load-velocity profiles and the contribution of the propulsive phase in the BP exercise at different ROMs.
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Performing the bench-press (BP) exercise in a weight stack machine (WSM) is a common practice. However, no previous studies have analysed the load-velocity relationship in this BP variant. The purpose of this study was 1) to investigate the load-velocity relationship during BP exercise using a WSM; and 2) to compare the load-velocity relationship in this exercise in two conditions: WSM vs. Smith machine (SM). Twenty-six young men performed a BP progressive loading test to determine their one-repetition maximum and load-velocity relationship using a WSM. Additionally, 19 participants performed two progressive loading tests (WSM and SM). A high relationship was found between the relative load (%1RM) and mean propulsive velocity (MPV) (R2 = 0.97; SEE = 0.07 m/s) in the WSM. Moreover, significant differences were observed (p <.05) in the MPV values attained in every %1RM in WSM and SM from 30 to 75% 1RM. The close relationship between the MPV values and the %1RM in BP exercise using a WSM enables coaches to use the MPV to accurately monitor their athletes on a daily basis. The differences observed between WSM and SM in the %1RM and their respective MPVs indicate that different equations must be used for each exercise mode.
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The aim of this study was to determine the effect of time-of-day on sprint swimming performance and on upper and lower body, maximum strength, and muscle power. Twelve well-trained junior swimmers (six male and six female) were tested for bench press (BP) maximum strength and muscle power, jump height countermovement vertical jump (CMJ), crank-arm peak power (10s Wingate test), and time to complete 25 m freestyle at 10:00 am and at 18:00 pm in a random order. Performance was significantly enhanced in the pm compared to the am in 25 m swimming time (1.7%; p = 0.01), BP maximum strength (3.6%, p = 0.04, ES = 1.87), BP muscle power (5.1%, p = 0.00, ES = 2.10), and CMJ height (5.8%; p = 0.02), but not in crank-arm power (4.1%; p = 0.08). Time-of-day increased swimming performance in a magnitude of one-third of the effects observed on upper and lower neuromuscular power, which suggests that factors beyond peak muscle power (i.e. swimming technique) affect 25 m freestyle performance.
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The purpose of the present study was to examine the influence of muscle group location and gender on the reliability of assessing the one-repetition maximum (1RM) test. Thirty healthy males (n = 15) and females (n = 15) who experienced at least 3 months of continuous resistance training during the last 2 years aged 18-35 years volunteered to participate in the study. The 1RM for the biceps curl, lat pull down, bench press, leg curl, hip flexion, triceps extension, shoulder press, low row, leg extension, hip extension, leg press and squat were measured twice by a trained professional using a standard published protocol. Biceps curl, lat pull down, bench press, leg curl, hip flexion, and squat 1RM's were measured on the first visit, then 48 hours later, subjects returned for their second visit. During their second visit, 1RM of triceps extension, shoulder press, low row, leg extension, hip extension, and leg press were measured. One week from the second visit, participants completed the 1 RM testing as previously done during the first and second visits. The third and fourth visits were separated by 48 hours as well. All four visits to the laboratory were at the same time of day. A high intraclass correlation coefficient (ICC > 0.91) was found for all exercises, independent of gender and muscle group size or location, however there was a significant interaction for muscle group location (upper body vs. lower body) in females (p < 0.027). In conclusion, a standardized 1RM testing protocol with a short warm-up and familiarization period is a reliable measurement to assess muscle strength changes regardless of muscle group location or gender.
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Purpose: The purpose of this study was to determine the oral dose of caffeine needed to increase muscle force and power output during all-out single multijoint movements. Methods: Thirteen resistance-trained men underwent a battery of muscle strength and power tests in a randomized, double-blind, crossover design, under four different conditions: (a) placebo ingestion (PLAC) or with caffeine ingestion at doses of (b) 3 mg · kg(-1) body weight (CAFF 3mg), (c) 6 mg · kg(-1) (CAFF 6mg), and (d) 9 mg · kg(-1) (CAFF 9mg). The muscle strength and power tests consisted in the measurement of bar displacement velocity and muscle power output during free-weight full-squat (SQ) and bench press (BP) exercises against four incremental loads (25%, 50%, 75%, and 90% one-repetition maximum [1RM]). Cycling peak power output was measured using a 4-s inertial load test. Caffeine side effects were evaluated at the end of each trial and 24 h later. Results: Mean propulsive velocity at light loads (25%-50% 1RM) increased significantly above PLAC for all caffeine doses (5.4%-8.5%, P = 0.039-0.003). At the medium load (75% 1RM), CAFF 3mg did not improve SQ or BP muscle power or BP velocity. CAFF 9mg was needed to enhance BP velocity and SQ power at the heaviest load (90% 1RM) and cycling peak power output (6.8%-11.7%, P = 0.03-0.05). The CAFF 9mg trial drastically increased the frequency of the adverse side effects (15%-62%). Conclusions: The ergogenic dose of caffeine required to enhance neuromuscular performance during a single all-out contraction depends on the magnitude of load used. A dose of 3 mg · kg(-1) is enough to improve high-velocity muscle actions against low loads, whereas a higher caffeine dose (9 mg · kg(-1)) is necessary against high loads, despite the appearance of adverse side effects.
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The 1-repetition maximum (1-RM) test is the gold standard test for evaluating maximal dynamic strength of groups of muscles. However, safety of actual 1-RM testing is questionable in clinical situations such as type 2 diabetes (T2D), where an estimated 1-RM test is preferred. It is unclear if acceptable test retest reliability exists for the estimated 1-RM test in middle aged T2D patients. This study examined the reliability of the estimated 1-RM strength test in untrained middle aged T2D subjects. Twenty five untrained diabetic males (n=19) and females (n=6) aged 40.7+0.4 years participated in the study. Participants undertook the first estimated 1-RM test for five exercises namely supine bench press, leg press, lateral pull, leg extension and seated biceps curls. A familiarisation session was provided three to five days before the first test. 1-RM was estimated for all participants by Brzycki 1-RM prediction equation. Another identical 1-RM estimation procedure occurred one week after first test. Intraclass correlation coefficients (ICC), paired t-test, standard error of measurement (SEM), Bland-Altman plots, and estimation of 95% CI were used to assess reliability. Test-retest reliability was excellent (ICC(2,1)=0.98-0.99) for all measurements with the highest for leg extension (ICC(2,1)=0.99). The SEM was lowest for lateral pull and leg extension exercises. Paired t-tests showed non-significant differences between the means of 2 sessions across three of five exercises. The study findings suggest that estimation of 1-RM is reliable for upper and lower body muscular strength measurement in untrained middle aged T2D patients.
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The purpose of this study was to investigate underlying mechanisms and neuromuscular recovery patterns following rapid and slow stretch-shortening cycle (SSC) movements performed to fatigue. Fourteen (10 moderately trained (MT) and four highly trained (HT)) subjects completed rapid and slow SSC movements to fatigue. The rapid SSC movement consisted of continuous drop jumps from a 30 cm platform until a predetermined jump height was no longer maintained, and the slow SSC movement consisted of continuous squats to 90° of knee flexion at a load of 65% of subject's one-repetition maximum until no further repetitions could be completed. Although blood lactate measures were significantly (p < 0.002) higher after the rapid SSC condition versus after the slow SSC condition, the recovery of neuromuscular properties (maximum voluntary contractions, twitch force, muscle compound action potential) following the two conditions to fatigue did not differ. The duration of the rapid SSC movement was dependent on the training status of the subject; HT subjects performed the rapid SSC longer (68.2%) than the MT subjects until fatigued. Thus, the neuromuscular fatigue recovery patterns were independent of the type of SSC movement, condition duration, and subject training status. Because rapid and slow SSC exercises induce similar fatigue patterns, training programs incorporating rapid SSC exercises can be developed similar to that prescribed in traditional slow SSC resistance training programs.
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To investigate whether caffeine ingestion counteracts the morning reduction in neuromuscular performance associated with the circadian rhythm pattern. Twelve highly resistance-trained men underwent a battery of neuromuscular tests under three different conditions; i) morning (10:00 a.m.) with caffeine ingestion (i.e., 3 mg kg(-1); AM(CAFF) trial); ii) morning (10:00 a.m.) with placebo ingestion (AM(PLAC) trial); and iii) afternoon (18:00 p.m.) with placebo ingestion (PM(PLAC) trial). A randomized, double-blind, crossover, placebo controlled experimental design was used, with all subjects serving as their own controls. The neuromuscular test battery consisted in the measurement of bar displacement velocity during free-weight full-squat (SQ) and bench press (BP) exercises against loads that elicit maximum strength (75% 1RM load) and muscle power adaptations (1 m s(-1) load). Isometric maximum voluntary contraction (MVC(LEG)) and isometric electrically evoked strength of the right knee (EVOK(LEG)) were measured to identify caffeine's action mechanisms. Steroid hormone levels (serum testosterone, cortisol and growth hormone) were evaluated at the beginning of each trial (PRE). In addition, plasma norepinephrine (NE) and epinephrine were measured PRE and at the end of each trial following a standardized intense (85% 1RM) 6 repetitions bout of SQ (POST). In the PM(PLAC) trial, dynamic muscle strength and power output were significantly enhanced compared with AM(PLAC) treatment (3.0%-7.5%; p≤0.05). During AM(CAFF) trial, muscle strength and power output increased above AM(PLAC) levels (4.6%-5.7%; p≤0.05) except for BP velocity with 1 m s(-1) load (p = 0.06). During AM(CAFF), EVOK(LEG) and NE (a surrogate of maximal muscle sympathetic nerve activation) were increased above AM(PLAC) trial (14.6% and 96.8% respectively; p≤0.05). These results indicate that caffeine ingestion reverses the morning neuromuscular declines in highly resistance-trained men, raising performance to the levels of the afternoon trial. Our electrical stimulation data, along with the NE values, suggest that caffeine increases neuromuscular performance having a direct effect in the muscle.
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Although the power clean test is routinely used to assess strength and power performance in adult athletes, the reliability of this measure in younger populations has not been examined. Therefore, the purpose of this study was to determine the reliability of the 1-repetition maximum (1RM) power clean in adolescent athletes. Thirty-six male athletes (age 15.9 ± 1.1 years, body mass 79.1 ± 20.3 kg, height 175.1 ±7.4 cm) who had >1 year of training experience in weightlifting exercises performed a 1RM power clean on 2 nonconsecutive days in the afternoon following standardized procedures. All test procedures were supervised by a senior level weightlifting coach and consisted of a systematic progression in test load until the maximum resistance that could be lifted for 1 repetition using proper exercise technique was determined. Data were analyzed using an intraclass correlation coefficient (ICC[2,k]), Pearson correlation coefficient (r), repeated measures analysis of variance, Bland-Altman plot, and typical error analyses. Analysis of the data revealed that the test measures were highly reliable demonstrating a test-retest ICC of 0.98 (95% confidence interval = 0.96-0.99). Testing also demonstrated a strong relationship between 1RM measures in trials 1 and 2 (r = 0.98, p < 0.0001) with no significant difference in power clean performance between trials (70.6 ± 19.8 vs. 69.8 ± 19.8 kg). Bland-Altman plots confirmed no systematic shift in 1RM between trials 1 and 2. The typical error to be expected between 1RM power clean trials is 2.9 kg, and a change of at least 8.0 kg is indicated to determine a real change in lifting performance between tests in young lifters. No injuries occurred during the study period, and the testing protocol was well tolerated by all the subjects. These findings indicate that 1RM power clean testing has a high degree of reproducibility in trained male adolescent athletes when standardized testing procedures are followed and qualified instruction is present.
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Countermovement jump (CMJ) has been extensively used in training, yet kinematic data for a large sample of trained athletes are limited. The aim of this study was to determine the relationship between kinematic factors of CMJ height in a large sample of trained track and field athletes. Forty-eight adult athletes performed 3 maximal CMJ-weighted jumps while ground reaction forces were sampled using a force platform synchronized with a linear transducer. The CMJ height presented significant relations with both eccentric (descending) and concentric (ascending) phases. In addition, strong correlations were observed between CMJ performance and the peak power produced during the concentric phase (r = 0.812-0.851) and with the average power generated in the same phase (r = 0.829-0.870). Finally, maximal negative velocity was low to moderate in its association with CMJ performance (r = 0.57-0.65). The present data contribute important knowledge concerning determinant factors of vertical jump performance that have not been analyzed in trained athletes. As predictors, it is important to observe high values of correlation between the force produced during the concentric and eccentric phases with the height of all the CMJ trials. In this way, our study confirms previous findings in which peak power was shown to be the best predictor of CMJ height. Nevertheless, the moderate but significant predictive value of negative velocity was even more noticeable.
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The purpose of this study was to examine the efficacy of 8 wk of resistance training to failure versus not to failure training regimens at both moderate and low volumes for increasing upper-body strength and power as well as cardiovascular parameters into a combined resistance and endurance periodized training scheme. Forty-three trained male rowers were matched and then randomly assigned to four groups that performed the same endurance training but differed on their resistance training regimen: four exercises leading to repetition failure (4RF; n = 14), four exercises not leading to failure (4NRF; n = 15), two exercises not to failure (2NRF; n = 6), and control group (C; n = 8). One-repetition maximum strength and maximal muscle power output during prone bench pull (BP), average power during a 20-min all-out row test (W 20 min), average row power output eliciting a blood lactate concentration of 4 mmol x L(-1) (W 4 mmol x L(-1)), and power output in 10 maximal strokes (W 10 strokes) were assessed before and after 8 wk of periodized training. 4NRF group experienced larger gains in one- repetition maximum strength and muscle power output (4.6% and 6.4%, respectively) in BP compared with both 4RF (2.1% and j1.2%) and 2NRF (0.6% and -0.6%). 4NRF and 2NRF groups experienced larger gains in W 10 strokes (3.6% and 5%) and in W 20 min (7.6% and 9%) compared with those found after 4RF (-0.1% and 4.6%), whereas no significant differences between groups were observed in the magnitude of changes in W 4 mmol x L(-1) (4NRF = 6.2%, 4RF = 5.3%, 2NRF = 6.8%, and C = 4.5%). An 8-wk linear periodized concurrent strength and endurance training program using a moderate number of repetitions not to failure (4NRF group) provides a favorable environment for achieving greater enhancements in strength, muscle power, and rowing performance when compared with higher training volumes of repetitions to failure in experienced highly trained rowers.
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Force platforms are used extensively to measure force and power output during countermovement jump (CMJ). The purpose of this study was to examine measurement reliability and validity of commonly used performance measurements derived from ground reaction force (GRF)-time data during CMJ and the influence of sampling at different frequencies. Twenty-four men performed 2 trials of CMJ on a force platform, and GRF-time data were sampled at a rate of 500 Hz. Data obtained at 500 Hz were considered as the reference, and then data were resampled at 400, 250, 200, 100, 50, and 25 Hz, using interpolation. Commonly used power, force, and velocity performance measures were obtained from GRF-time data. Reliability was assessed by intraclass correlation coefficient (ICC) and coefficient of variation (CV) between the 2 trials within the session. Peak power, peak force, and peak velocity were highly reliable across all sampling frequencies (ICC = 0.92-0.98, CV = 1.3-4.1). Percentage differences from 500-Hz reference values ranged from -0.85 to 0.20% at 400 Hz, -1.88 to 0.89% at 250 Hz, -1.80 to 1.31% at 200 Hz, -3.63 to 3.34% at 100 Hz, -11.37 to 6.51% at 50 Hz, and -13.17 to 9.03% at 25 Hz. In conclusion, peak power, force, and velocity measurements derived from GRF to assess leg extensor capabilities are reliable within a test session except for peak rate of force development and time to peak power. With regard to sampling frequency, scientists and practitioners may consider sampling as low as 200 Hz, depending on the purpose of measurement, because the percentage difference is not markedly enlarged until the frequency is 100 Hz or lower.
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The aims in this review are: (1) to identify physiological determinants of performance; (2) to consider training specificity by examining aerobic, team and racket sports, strength and power activities, and cross-training and concurrent training methods; and (3) to evaluate the role of specificity in the physiological assessment of performance determinants. Assessment of the physiological determinants of performance is an integral part of sports science support for elite athletes. Laboratory and field-based physiological assessments are fundamental elements in profiling athletes, assessing training adaptations, and interrogating programme efficacy. The relatively small and highly specific adaptations associated with high-performance training call for valid, reliable, and sensitive methods of assessment. Recent advances in the physiological assessment of athletes have led to the development of a plethora of laboratory and field-based procedures. In the assessment of the athlete, there is a tension between the high reliability and low ecological validity of laboratory assessments and the low reliability and high validity of field-based methods. In an attempt to enhance ecological validity of training and physiological assessment, various sports-specific ergometers have been designed. This development has helped to match fitness assessment procedures to the demands of the sport concerned.
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Twelve experienced male weight lifters of varying ability completed a series of bench press lifts at 95% of maximum. These lifts included a rebound bench press, which was performed without a delay between the downward and upward components of the lift, a bench press performed without a downward phase, and two bench press movements performed with various pause periods imposed between the downward and upward phases of the lift. Force and cinematographic data were collected during each lift. The augmentation to performance derived from prior stretch was observed to decay as a function of the pause duration. This relationship was accurately described (P less than 0.01) by a negative exponential equation with a half-life of 0.85 s. The nature of this decay is discussed with reference to the implications for stretch-shorten cycle movements that are performed with a period of pause between the eccentric and concentric phases and for stretch-shorten cycle research paradigms.
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Twelve experienced male weight lifters performed a rebound bench press and a purely concentric bench press lift. Data were obtained pertaining to 1) the benefits to concentric motion derived from a prior stretch and 2) the movement frequency adopted during performance of the stretch-shorten cycle (SSC) portion of the rebound bench press lift. The subjects also performed a series of quasi-static muscular actions in a position specific to the bench press movement. A brief perturbation was applied to the bar while these isometric efforts were maintained, and the resulting damped oscillations provided data pertaining to each subject's series elastic component (SEC) stiffness and natural frequency of oscillation. A significant correlation (r = -0.718, P less than 0.01) between maximal SEC stiffness and augmentation to concentric motion derived from prior stretch was observed. Subjects were also observed to perform the SSC portion of the rebound bench press movement to coincide with the natural frequency of oscillation of their SEC. These results are interpreted as demonstrating that the optimal stiffness in a rebound bench press lift was a resonant-compliant SEC.